LONG: Faster revs, not more revs...

THIS IS AN ENGINEERING EXERCISE, NOT A BUILD DIARY.
GEN III+ based engine.
Trying to go from idle to red line under full throttle milliseconds faster. So we are not "revving to the moon" just revving to 7,500 REALLY FAST. Think super bike throttle response. Let's assume that this is in a stand, so there is no confusion on transmission choices, weight of vehicle or gear ratios. Motor plus flywheel, only accessory drives are water pump, alternator.

Naturally Aspirated
11:1 Compression Ratio
91 octane
7,500 RPM red line
Hydraulic lifters
Aluminum (4 bolt head) block
2 valve heads

Everything else goes.

So - in order to build this there are certain things a person can do in order to achieve faster revs. Lets start out...

1. Shorten stroke - this brings the outermost swing of the crankshaft more in line with the center line of the crankshaft, therefore allowing faster revving at the expense of torque and displacement. This could even be done with the shortest stroke crank available (4.8 crank AFAIK at 83 MM) offset ground to reduce stroke and reciprocating mass simultaneously if using different rods...

2. Lighten/blueprint/balance reciprocating assembly - including (but not limited to) aluminum flywheel, custom flyweight pistons, aluminum or titanium rods...

3. Reduce reciprocating drag - knife edge and polish crankshaft, windage scrapers, synthetic lower viscosity oil...

4. Increase air flow - Higher flow from intake, heads, and exhaust. How much flow (if any amount) is too much considering the red line? In order to increase the flow to the maximum allowed by two valves one needs the largest valves that will fit. The best I have found is the LSX-DR heads 19166979 (http://www.crateenginedepot.com/stor...P2572C114.aspx) but they are a 6 bolt head. I know that the 4 bolt heads work on the LSX blocks, but do the 6 bolt heads work (even with slight modification) on the 4 bolt block? I read somewhere that these will flow 430+ CFM intake side (at like .8" lift !) and they claim to be good for 900+ NA HP. If they do not work as a 6 bolt head on a 4 bolt block then the next best I see are the LS6 CNC ported 88958665 (http://www.crateenginedepot.com/stor...-P852C114.aspx) though I may have missed something. They claim these are good for 500+ HP and they will flow 304 at .570 lift. NOW - that being said, the former heads require a minimum 4.125" bore whereas the latter heads will fit a stock bottom end of any GEN III+. That being said, the increased bore is a good thing in one respect because it allows not only the largest valves but it also prevents shrouding of said valves. If a person uses Darton sleeves the bore can be increased up to 4.200". This would allow maximum valve diameter and either head (assuming you can in fact use a 6 bolt head on a 4 bolt block) with minimal valve shrouding. ON THE OTHER HAND, the larger bore requires more air all other things being equal. More air means more TIME to fill the chamber, which may in turn mean an incomplete fill for a given time (inefficient) or more time for the increased volume. Then at what point (given a de-stroked motor) is the displacement a limiting factor on the given flow numbers. Also keep in mind that the flow numbers given are peak and an average flow will be considerable less. Additionally, the .8" lift of the DR heads is probably unrealistic. Add to this the chamber differences (50cc for the DR and 65cc for the CNC'd LS6) and we run into changing piston dish to maintain the 11:1 ratio. So the head choice is as clear as mud.

5. Valve train - Assuming that we are using the lightest weight components that we can, then to lighten anything further would be to use smaller valves, allowing weaker springs to limit mechanical losses. Would it make more sense to use the stronger springs to control the valves better? Also, where is the trade off for small, light valves and flow? Roller everything in the valve train? Speaking of which, is it better to use a dog bone timing set or a double roller? I would think that the double roller chain would be the most efficient, but I do not know. Taking the valve train the the extreme I know that some of the piston engine fighter planes from circa WWII even hollowed the camshafts.

6. Under drives - The most aggressive accessory under drives that I know of are 25% - like the ATI 918847. Take this further and put on the smallest alternator available. Is there a MECHANICAL water pump that takes less power to run than others? I have even heard of people under driving their oil pump, though I cannot find that link now...

7. Electronic tuning - I know little to nothing about this, so inform me.

THOUGHTS or SUGGESTIONS?

P.S. - If you do not want to follow the beginning "rules" to this theoretical build, go elsewhere. I don't need to be told that you can make more power with a 14:1 454 LSX.

Also, sorry about being so long-winded.

Quote:

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Originally Posted by Lincolnman

THIS IS AN ENGINEERING EXERCISE, NOT A BUILD DIARY.
GEN III based engine.
Trying to go from idle to red line under full throttle milliseconds faster. So we are not "revving to the moon" just revving to 7,500 REALLY FAST. Think super bike throttle response. Let's assume that this is in a stand, so there is no confusion on transmission choices, weight of vehicle or gear ratios. Motor plus flywheel, only accessory drives are water pump, alternator.

Naturally Aspirated
11:1 Compression Ratio
91 octane
7,500 RPM red line
Hydraulic lifters
Aluminum (4 bolt head) block
2 valve heads

Everything else goes.

So - in order to build this there are certain things a person can do in order to achieve faster revs. Lets start out...

1. Shorten stroke - this brings the outermost swing of the crankshaft more in line with the center line of the crankshaft, therefore allowing faster revving at the expense of torque and displacement. This could even be done with the shortest stroke crank available (4.8 crank AFAIK at 83 MM) offset ground to reduce stroke and reciprocating mass simultaneously if using different rods...

2. Lighten/blueprint/balance reciprocating assembly - including (but not limited to) aluminum flywheel, custom flyweight pistons, aluminum or titanium rods...

3. Reduce reciprocating drag - knife edge and polish crankshaft, windage scrapers, synthetic lower viscosity oil...

4. Increase air flow - Higher flow from intake, heads, and exhaust. How much flow (if any amount) is too much considering the red line? In order to increase the flow to the maximum allowed by two valves one needs the largest valves that will fit. The best I have found is the LSX-DR heads 19166979 (http://www.crateenginedepot.com/stor...P2572C114.aspx) but they are a 6 bolt head. I know that the 4 bolt heads work on the LSX blocks, but do the 6 bolt heads work (even with slight modification) on the 4 bolt block? I read somewhere that these will flow 430+ CFM intake side (at like .8" lift !) and they claim to be good for 900+ NA HP. If they do not work as a 6 bolt head on a 4 bolt block then the next best I see are the LS6 CNC ported 88958665 (http://www.crateenginedepot.com/stor...-P852C114.aspx) though I may have missed something. They claim these are good for 500+ HP and they will flow 304 at .570 lift. NOW - that being said, the former heads require a minimum 4.125" bore whereas the latter heads will fit a stock bottom end of any GEN III. That being said, the increased bore is a good thing in one respect because it allows not only the largest valves but it also prevents shrouding of said valves. If a person uses Darton sleeves the bore can be increased up to 4.200". This would allow maximum valve diameter and either head (assuming you can in fact use a 6 bolt head on a 4 bolt block) with minimal valve shrouding. ON THE OTHER HAND, the larger bore requires more air all other things being equal. More air means more TIME to fill the chamber, which may in turn mean an incomplete fill for a given time (inefficient) or more time for the increased volume. Then at what point (given a de-stroked motor) is the displacement a limiting factor on the given flow numbers. Also keep in mind that the flow numbers given are peak and an average flow will be considerable less. Additionally, the .8" lift of the DR heads is probably unrealistic. Add to this the chamber differences (50cc for the DR and 65cc for the CNC'd LS6) and we run into changing piston dish to maintain the 11:1 ratio. So the head choice is as clear as mud.

5. Valve train - Assuming that we are using the lightest weight components that we can, then to lighten anything further would be to use smaller valves, allowing weaker springs to limit mechanical losses. Would it make more sense to use the stronger springs to control the valves better? Also, where is the trade off for small, light valves and flow? Roller everything in the valve train? Speaking of which, is it better to use a dog bone timing set or a double roller? I would think that the double roller chain would be the most efficient, but I do not know. Taking the valve train the the extreme I know that some of the piston engine fighter planes from circa WWII even hollowed the camshafts.

6. Under drives - The most aggressive accessory under drives that I know of are 25% - like the ATI 918847. Take this further and put on the smallest alternator available. Is there a MECHANICAL water pump that takes less power to run than others? I have even heard of people under driving their oil pump, though I cannot find that link now...

7. Electronic tuning - I know little to nothing about this, so inform me.

THOUGHTS or SUGGESTIONS?

P.S. - If you do not want to follow the beginning "rules" to this theoretical build, go elsewhere. I don't need to be told that you can make more power with a 14:1 454 LSX.

Also, sorry about being so long-winded.

---

There is a guy on LS1tech who has been building quick, higher revving motors by boring and destroking ls motors. To me, it seems like you're wanting to build a 377 SBC type of motor. Quick/high revs.

Why the target to maintain 11:1?

Under #4, you need to include a vacuum pump to evacuate the crank case. Without the extra air in there to push around, things tend to move faster.

As far as revving quicker, lighter is better. Where ever you can reduce weight safely, the quicker it will rev.

I would try a 6.0 or 6.2 block with a 4.8 crank for a bottom end assy with lightweight rods and pistons..

For an intake manifold you should chose ITB's
the most aggressive under drive i know of is this ati for ASA racing and its at 60% (useless for street use)
http://cgi.ebay.com/ebaymotors/ATI-9...item3cb3683b7b

Do you have any idea what the guy's name on LS1tech is?
If by 377 SBC you are referring to a 400 block and 350 crank, yes - same idea.
I consider 11:1 to be the threshold for 91 octane compression. More compression generally means more power so I figured it made sense to run all the way up to the maximum practical limit there. Also, higher compression keeps the throttle response snappy so that it doesn't "hang" at higher RPM for an undue period of time. I have also read that you can modify your IAC to help drop RPM quickly after rev up, but I don't know how that works.
I understand the logic behind the vacuum pump, but wouldn't that mean more parasitic loss to running the pump than just directly moving the crankcase air?
Yeah, 6.0 or 6.2 was considered, I guess I said Gen III but I just meant Gen III+. I had thought about a 6.0 Darton sleeved block at 4.200" bore and either a stock or (reverse) offset ground 4.8 crank. Since the RPM limit is 7,500 I think that the stock crank should hold up fine, if offset ground I am less knowledgeable on their strength limit. Also, I have no idea what rods could be used with an offset grind. Some import part in a custom length?
ITBs? What does this mean, individual throttle bores? I see from a cursory search of Google images that most images for it appear to be velocity stacks and the like...
60% underdrive - WOW. Out of curiosity, is it useless for street because of inadequate cooling from the pump running too slow, inadequate charging for the same reason, or both?
Any thoughts on the small/light/light spring vs larger (and inherently heavier) valves and springs?
What about the dog bone vs double roller timing set?
...and will the 6 bolt heads work on a 4 bolt clock or not?
Thanks for the replies guys! Keep 'em coming!

You are asking some very specific questions that relatively few people really know the decisive answers too. But considering this is a relatively small forum that focuses on moving heavy trucks around I doubt you will find much info here you didn't already know. With the acception of tuning info since you said you know nothing about that. Nelson or farmtruck seems to be the resident expert on that subject. However I would suggest you post this same question over on ls1 tech. They seem to like getting into deep theoretical discussions and there are alot of members over there that have knowledge to the point where I can barely follow what they are talking about. And I have been to auto diesel college and have been turning wrenches for a living since I was 15.

ITB= individual throttle body's (one per cylinder) here's a link to a Toyota v8 with itbs, notice the fast revs and throttle response
http://www.youtube.com/watch?v=Fm5k1ntJNBU
the 60% under drive would be useless because of both reasons, at a idle of 700 rpm your alt and water pump would be spinning 280 rpm and at highway speed (2000 rpm) every thing would be spinning at 800 rpm

i understand what youre wanting and trying to accomplish, i wont go in to detail but i will say as long as the valvetrain is as light as possible you would beable to spin the rpms up, i myself is building a 410 with a lunati pro series crank and rods and the lightess pistons found, with this in mind the topend has to match, light weight everything valves, rockers, springs, locks ( everything )


bottom line, its not cheap when you start hitting 8k rpms or above

Quote:

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Originally Posted by Lincolnman

Do you have any idea what the guy's name on LS1tech is?
If by 377 SBC you are referring to a 400 block and 350 crank, yes - same idea.
I consider 11:1 to be the threshold for 91 octane compression. More compression generally means more power so I figured it made sense to run all the way up to the maximum practical limit there. Also, higher compression keeps the throttle response snappy so that it doesn't "hang" at higher RPM for an undue period of time. I have also read that you can modify your IAC to help drop RPM quickly after rev up, but I don't know how that works.
I understand the logic behind the vacuum pump, but wouldn't that mean more parasitic loss to running the pump than just directly moving the crankcase air?
Yeah, 6.0 or 6.2 was considered, I guess I said Gen III but I just meant Gen III+. I had thought about a 6.0 Darton sleeved block at 4.200" bore and either a stock or (reverse) offset ground 4.8 crank. Since the RPM limit is 7,500 I think that the stock crank should hold up fine, if offset ground I am less knowledgeable on their strength limit. Also, I have no idea what rods could be used with an offset grind. Some import part in a custom length?
ITBs? What does this mean, individual throttle bores? I see from a cursory search of Google images that most images for it appear to be velocity stacks and the like...
60% underdrive - WOW. Out of curiosity, is it useless for street because of inadequate cooling from the pump running too slow, inadequate charging for the same reason, or both?
Any thoughts on the small/light/light spring vs larger (and inherently heavier) valves and springs?
What about the dog bone vs double roller timing set?
...and will the 6 bolt heads work on a 4 bolt clock or not?
Thanks for the replies guys! Keep 'em coming!

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Yes, the 400 block with 350 crank setup. RetroLSx is the one doing the motors. Here's a link to his forums. They aren't very active and I don't know his exact name on LS1tech.

Sorry for the really technical questions, that's just the way my mind is wired. I understand that the forum is intended for trucks and that this build is contrary to the conventional thinking, especially considering the weight of your vehicles. I am not a member of LS1Tech (yet) and I joined over here because I ALSO own a 1993 K3500 that will be getting a Gen III+ motor (totally independent of this theory based build). I just thought that you guys would be a good place to begin asking. I have seen Nelson's name tossed around quite a bit on the forums, and when I do my truck I will likely look to him for a tune, but this thread is about different breed of build. I will look into LS1Tech more, though. "They seem to like getting into deep theoretical discussions and there are alot of members over there that have knowledge to the point where I can barely follow what they are talking about." I have had that feeling on other forums before, I know what you mean.
ITB - okay, so that was what I was thinking I just said bore rather than body. Thank you for the video link, I will look into ITB setups more. I had kind of guessed that the 60% under drive would be totally useless, but I thought I would ask anyway.
Skeet, you have the right idea, I think. I am just trying to hammer out ALL the potential little possibilities for a "total picture" build. (STILL THEORY ONLY!)
Thanks again, guys. I'm off to LS1Tech, but I'll be back!

this thread intrigues me...mainly because I also am always having ideas on theoretical builds for my own projects and always like seeing other people's ideas. I have to say though I'm surprised nobody has mentioned using a full roller valvetrain (unless I overlooked it or it was simply assumed in use) for reduction of friction and quicker response.

http://www.retrolsx.com/forums/


Ooops. I forgot to post the link!

Quote:

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Originally Posted by Slammed96

this thread intrigues me...mainly because I also am always having ideas on theoretical builds for my own projects and always like seeing other people's ideas. I have to say though I'm surprised nobody has mentioned using a full roller valvetrain (unless I overlooked it or it was simply assumed in use) for reduction of friction and quicker response.

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i was gonna mention it but i got the impression was the guy was set on hydraulic roller :(

good post though

Justin, I hate you. And he stated that he would be using a full roller valvetrain.

Quote:

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Originally Posted by Duct_tape123

Justin, I hate you. And he stated that he would be using a full roller valvetrain.

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hmmm...i must not have read it very well then...what i get for staying up late killin time on here

Quote:

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Originally Posted by Lincolnman

... I understand the logic behind the vacuum pump, but wouldn't that mean more parasitic loss to running the pump than just directly moving the crankcase air? ...

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The vacuum pump is electric and causes no parasitic losses. I would bet every hard core racer out there is running one (or should be). It also helps the rings seal better as well.

There are guys running 11.5:1 + compression, but that is on 93.

I was planning on doing this a little on the cheaper side, with a 4.8 bored out to LS1 specs. Gives you a 313, and the same bore/stroke ratio as some other revving V8s, like 289's, 302's, 340's

http://www.youtube.com/watch?v=BZHCTBkcNsM

Retrofitted ITBs on a LS2,

Quote:

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Originally Posted by Slammed96

this thread intrigues me...mainly because I also am always having ideas on theoretical builds for my own projects and always like seeing other people's ideas. I have to say though I'm surprised nobody has mentioned using a full roller valvetrain (unless I overlooked it or it was simply assumed in use) for reduction of friction and quicker response.

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Yes, I had figured on roller valve train. I wanted to think of this in terms of roller hydraulic lifters. Since the engine would not ever see over 7,500 I had figured that should be sufficient. Is there any advantage to the solid lifters other than higher (beyond 7,500) RPM? I cannot see how it should matter up to the proven 7,500 RPM, beyond that - who cares? That's the rev limiter.

Quote:

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Originally Posted by Paulster2

The vacuum pump is electric and causes no parasitic losses. I would bet every hard core racer out there is running one (or should be). It also helps the rings seal better as well.

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Well, that would be a parasitic loss in the long run. For one drag race this would mean that the pump just dragged down the battery, but if it was in a road racer or an endurance vehicle, it would need to work the alternator harder. That's parasitic loss right there. I admit I had not specified long term runs in the opening post, but if it were not for that the 60% under drive would be okay, too. So I still see this as a net loss.

Quote:

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Originally Posted by SCIV

There are guys running 11.5:1 + compression, but that is on 93.

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Can only get 91 octane, 93 octane (10% ethanol) or 110 (?) octane ($$$) reliably around here. 93 straight I have yet to see, so I figured the design parameters around what's readily available.

Quote:

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Originally Posted by Mr.Cornelius

http://www.youtube.com/watch?v=BZHCTBkcNsM

Retrofitted ITBs on a LS2,

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Thanks for the link, but I actually just found that last night. I did some reading on ITBs, they sound like a real nightmare to keep adjusted and they don't put filters on them (effectively) that even keep out low flying birds. They are wicked cool, though!

P.S. I guess to join LS1Tech a person just needs an account with Google, Yahoo, or some others. That was easy - same user name if anyone cares.

guessing with hydraulic rollers it should be fine, seeing as the rpm will never be astronomical.

but because this is a theory based thread, I have an idea for a retrofit that may help with the windup and certainly help with power. I was talking to a friend the other day about a turbo-esq setup that is linked to the snout of the crank via gear drive and uses the same principals as a turbo, but instead of making boost it aids in spinning the crank. This way you gain back much power lost by friction and parasitic drag caused by accessories. I have also heard of this setup simultaneously running a supercharger as well. Though I have never seen it put to use on a vehicle or standard V block engine, I know it was used on some WWII era radial engine planes. I think it would be interesting to see if and how it would work for a street or race application.

Quote:

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Originally Posted by Slammed96

I was talking to a friend the other day about a turbo-esq setup that is linked to the snout of the crank via gear drive and uses the same principals as a turbo, but instead of making boost it aids in spinning the crank. This way you gain back much power lost by friction and parasitic drag caused by accessories. I have also heard of this setup simultaneously running a supercharger as well. Though I have never seen it put to use on a vehicle or standard V block engine, I know it was used on some WWII era radial engine planes. I think it would be interesting to see if and how it would work for a street or race application.

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Cool concept - I would not have thought of it.

Quote:

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Originally Posted by Lincolnman

... Well, that would be a parasitic loss in the long run. For one drag race this would mean that the pump just dragged down the battery, but if it was in a road racer or an endurance vehicle, it would need to work the alternator harder. That's parasitic loss right there. I admit I had not specified long term runs in the opening post, but if it were not for that the 60% under drive would be okay, too. So I still see this as a net loss ...

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Wow, really? You have to be pulling my leg? How much juice do you think it takes to draw down a vacuum? Less than running your a factory car stereo. I'm telling you no parasitic losses on this. I'll make it really simple ... you should see gains of 10-15rwhp with this addition. No parasitic losses.

If you're worried about something as small as a vac pump, better unhook the headlights, radio, and pretty much anything else.

Quote:

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Originally Posted by Lincolnman

Cool concept - I would not have thought of it.

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its one of those things that really only makes sense after you hear it from another person, I can honestly say I would never have thought of it either. Someday I would really like to see it tried out, or possibly fab something up for myself to get it to work...also sorry to kinda get fixed on a tangent, I just have alot of interest in this haha

Quote:

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Originally Posted by Slammed96

... I was talking to a friend the other day about a turbo-esq setup that is linked to the snout of the crank via gear drive and uses the same principals as a turbo, but instead of making boost it aids in spinning the crank.

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Just a side thought on this, how does one make it work considering the RPM of a turbo? Are we talking about a turbo running what would basically amount to an air to air torque converter or what? I don't imagine that you could run gears and get proper oiling, and a chain or belt would disintegrate.

Quote:

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Originally Posted by Paulster2

Wow, really? You have to be pulling my leg? How much juice do you think it takes to draw down a vacuum? Less than running your a factory car stereo. I'm telling you no parasitic losses on this. I'll make it really simple ... you should see gains of 10-15rwhp with this addition. No parasitic losses.

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I was not suggesting that it was a bad idea, just that it MIGHT have some trade off. No, I am not pulling your leg. I know that there will be parasitic loss, and it ought to be more so even then if a person ran a vacuum pump directly as an accessory, because the conversion from mechanical to electric and back to mechanical would lead to significant losses not found in a mechanical to mechanical conversion. I might be missing something there like the losses from the alternator creating the electricity and the electric pump COULD be more efficient (pending mechanical pump option) but it seems illogical. ALL THAT SAID - I do believe that it makes more power, but as more power was not the end goal here, faster RPM were, I am not sure it fits. That being said I would probably do it (in a real world situation) anyway, because I do believe that the marginal losses would be FAR AND AWAY outweighed by the overall performance increase.
It just didn't fit the mold of this question perfectly, that's all.

Quote:

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Originally Posted by pl4yboy

If you're worried about something as small as a vac pump, better unhook the headlights, radio, and pretty much anything else.

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Who said anything about those being on anything (or even existing relative to this) at all? I don't recall saying that this was going to be installed in my daily driver. Not to be a jerk, but it was not what I had asked about.

New thought - what about chain driven accessories? Chains are considerably more efficient than a rubber belt...

Lincoln, did you get my pm?

Quote:

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Originally Posted by Lincolnman

Who said anything about those being on anything (or even existing relative to this) at all? I don't recall saying that this was going to be installed in my daily driver. Not to be a jerk, but it was not what I had asked about.

New thought - what about chain driven accessories? Chains are considerably more efficient than a rubber belt...

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I just thought you should take everything into account. I assume when building a motor (especially when you specify LS platform) that it will go in to something. If the motor was going into something, I would assume it would have electronics of sorts. Headlights are a must if you plan on driving it at night. The majority of vehicles have a stereo (Hell my Polaris Ranger has a stereo). Just food for thought. No need to get your panties in a bunch.

I assumed this is a concept engine for some type of competition go-kart, not a vehicle driven on any road. The SAE organizations have minimal amounts of electronics: starter, alternator, battery. Lincoln, you never specified the application for the motor. What is it for?

Quote:

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Originally Posted by cjriojas

Lincoln, did you get my pm?

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No. No I didn't.

Quote:

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Originally Posted by pl4yboy

I just thought you should take everything into account. I assume when building a motor (especially when you specify LS platform) that it will go in to something. If the motor was going into something, I would assume it would have electronics of sorts. Headlights are a must if you plan on driving it at night. The majority of vehicles have a stereo (Hell my Polaris Ranger has a stereo). Just food for thought. No need to get your panties in a bunch.

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No bunching, just saying. Your assumptions are safe ones, but I was worried about things getting off on a tangent and eventually degrading into a thread-jacking. Hence I wanted to stay on point.

Quote:

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Originally Posted by cjriojas

I assumed this is a concept engine for some type of competition go-kart, not a vehicle driven on any road. The SAE organizations have minimal amounts of electronics: starter, alternator, battery. Lincoln, you never specified the application for the motor. What is it for?

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That's why I said theoretical, so people's minds would not be clouded by application data. Yes, a competition cart is the closest practical application to what I was thinking.

PM sent