Question for those experienced in boosting.

[Xanthos]

Planning on doing a twin turbo setup on the V6 camaro that I purchase (once I cut open the fender gills I'll need something to use that newfound airflow for, right?). However, I can't decide whether I want to do a 5 psi setup, or a 9 psi setup. I understand the obvious - 9 psi will produce more power than 5 psi. The not-so-obvious though, is what I'm not sure about.

A) I don't want to modify the engine internals in any way, except possibly some higher flow injectors. I would be worried about pre-ignition, but the VVT *should* take care of that if my understanding of the system is correct.

B) I don't want to hurt fuel economy very much - namely, as long as I can keep my foot out of it, I don't want it to have any worse fuel economy than the stock car did. I don't mind running 89 octane fuel, however (but, as I said above, the VVT *should* make this only necessary to gain more power)

My total goal is to reach a 13 second ET, without changing the stock internals or using a more aggressive tune (was going to have the car tuned after the turbos, but back to the stock A/F ratios). I *think* this should be possible with a 5 psi setup, but I'm fairly certain it will be at 9 psi. SO... mostly I want to know if 9 psi would be a bad idea...
- Xanthos

[CamaroSpike23]

yes and no. yes its a bad idea, for one important fact. you dont want to change the internals, yet you want to run FI on a motor with a c/r of over 11:1. ideally, 9.5:1 or so is the best you wanna run for boosted applications.


your goal is 13s... easy. take every thing that isnt bolted down to the car out, throw on a CAI and some slicks and take it to the track. she will make it.

[Mr. Wyndham]

Originally Posted by CamaroSpike23

yes and no. yes its a bad idea, for one important fact. you dont want to change the internals, yet you want to run FI on a motor with a c/r of over 11:1. ideally, 9.5:1 or so is the best you wanna run for boosted applications.

Even you must take account for Direct Injection, spike.
It cools the charge for one, it also sprays right before the end of compression (so for the most part, all you're compressing is air).
AND, they don't even reccomend premium for this engine, so I think it's safe to assume that there's wiggle room for FI once somebody gets the computer tuning down.

DI is a whole new game.......


fwiw; I'm no expert -- but I've read quite a bit on this, if that means anything -- I think you could run 5psi without breaking anything; but I wouldn't go any higher...

[CamaroSpike23]

Originally Posted by Dragoneye

Even you must take account for Direct Injection, spike.
It cools the charge for one, it also sprays right before the end of compression (so for the most part, all you're compressing is air).
AND, they don't even reccomend premium for this engine, so I think it's safe to assume that there's wiggle room for FI once somebody gets the computer tuning down.

DI is a whole new game.......


fwiw; I'm no expert -- but I've read quite a bit on this, if that means anything -- I think you could run 5psi without breaking anything; but I wouldn't go any higher...

im not saying that its bad to do it because of the DI/cr. im saying that by putting boost on a motor that already has a static cr of 12:1 is going to be tricky to say the least. there's this little thing called......oh......wait.....ummmmmm....... oh yeah, blown head gaskets/seals/heads in general/valve stems/valves etc. thats why i made the comment about having the ideal cr at 9.5 or so. any higher than that, and you need to watch how much you turn up the boost or you're gonna blow something up...literally, up, up and away

[Mr. Wyndham]

Well, that makes sense...but Turbo-deisels aren't regularly blowing up - and those have...what, 15:1+ CRs? Again, I'm no "expert"; just putting it out there.

[Xanthos]

I'm not looking for extreme amounts of boost - I'm not saying "This is the amount of boost I want and heres what I want to do to get there," I'm saying "I want as much boost as I can safely create without modifying the internals." If thats 5 psi, so be it. If its 9 psi, all the better. Now, I can't get away with tearing out everything that isn't bolted on, or putting on slicks, because this will be my daily driver. I know people do it, and drive it around everywhere too, but it would be too much for me to put up with all the time. Maybe I'll just wait and see if GM produces a turbo kit from GMPP... or worse case scenario, I can just replace the pistons with lower CR aftermarket bits...
- Xanthos

[CamaroSpike23]

Originally Posted by Dragoneye

Well, that makes sense...but Turbo-deisels aren't regularly blowing up - and those have...what, 15:1+ CRs? Again, I'm no "expert"; just putting it out there.

turbo diesels also have bigger blocks to start out with, they also work thru the diesel cycle instead of the otto cycle where diesels use compression ignition (which is actually detonation/knock, depending on how you look at it) instead of spark plugs. they are made to run with high compression....its the basis for operation for a diesel motor. i thought you knew that...

Originally Posted by XanthosV6

I'm not looking for extreme amounts of boost - I'm not saying "This is the amount of boost I want and heres what I want to do to get there," I'm saying "I want as much boost as I can safely create without modifying the internals." If thats 5 psi, so be it. If its 9 psi, all the better. Now, I can't get away with tearing out everything that isn't bolted on, or putting on slicks, because this will be my daily driver. I know people do it, and drive it around everywhere too, but it would be too much for me to put up with all the time. Maybe I'll just wait and see if GM produces a turbo kit from GMPP... or worse case scenario, I can just replace the pistons with lower CR aftermarket bits...
- Xanthos

5 psi should be fine, 9 psi intercooled would probably be ok as well, but it will be a "trial" and "blow your motor up" basis till you get it right. i wouldnt mess with it honestly. id much rather run a supercharger on the LS3...

but then again im not a big fan of turbos to begin with.


now when thinking forced induction...keep this pic in mind...

[Mr. Wyndham]

Originally Posted by CamaroSpike23

turbo diesels also have bigger blocks to start out with, they also work thru the diesel cycle instead of the otto cycle where diesels use compression ignition (which is actually detonation/knock, depending on how you look at it) instead of spark plugs. they are made to run with high compression....its the basis for operation for a diesel motor. i thought you knew that...

I do know that: diesel engines are basicall where direct inection originated. But you sounded like you were talking about the CR itself, not fuel, or ignition cycles...Still, like you said above about diesels: SIDI engines are made to run with high compression (relative to non-SIDI), right?

[Xanthos]

Thats an interesting question... I didn't think about using an intercooler... Intercooled systems make more power than non-intercooled systems, right? So maybe a 5 psi intercooled system would be enough power to reach a 13 et without changing out the engine components - especially if I run it on premium fuel, that way the engine doesn't have to retard the timing...
- Xanthos

[GTAHVIT]

I have to agree with spike. The thing you have to be concerned with is the Compression Ratio.

5 psi with the static CR will be safe reliable and a ton of fun.

9 psi with an inner cooler... That is on the edge of reliability and I would be nervous every time I went WOT.

But, I think if you understand that you can go either way.

[Xanthos]

Yeah... maybe I'll just go with 5 psi and an intercooler. If I need it faster than that, I can always lighten the flywheel and the crank pulley like I had originally wanted. And theres always premium gas when I want more power...
- Xanthos

[MAROobsession]

i have a feeling with a tt kit and some bolt ons you'd be able to break into 12's

[The_Blur]

Start with traction modifications, and go from there. You will surprise yourself with the time improvements just from mounts, strut bats, and stuff like that.

Everything else you propose would be kind of dangerous. I don't know the limits of the LLT internals, but I imagine you'd be much better off rebuilding the motor for this. You're looking at a serious project, and you should aim high for performance. What you want can be done, but you don't want to push your motor too hard without backing it up with top notch parts, like pistons and connecting rods.

[DGthe3]

Originally Posted by XanthosV6

Planning on doing a twin turbo setup on the V6 camaro that I purchase (once I cut open the fender gills I'll need something to use that newfound airflow for, right?). However, I can't decide whether I want to do a 5 psi setup, or a 9 psi setup. I understand the obvious - 9 psi will produce more power than 5 psi. The not-so-obvious though, is what I'm not sure about.

A) I don't want to modify the engine internals in any way, except possibly some higher flow injectors. I would be worried about pre-ignition, but the VVT *should* take care of that if my understanding of the system is correct.

B) I don't want to hurt fuel economy very much - namely, as long as I can keep my foot out of it, I don't want it to have any worse fuel economy than the stock car did. I don't mind running 89 octane fuel, however (but, as I said above, the VVT *should* make this only necessary to gain more power)

My total goal is to reach a 13 second ET, without changing the stock internals or using a more aggressive tune (was going to have the car tuned after the turbos, but back to the stock A/F ratios). I *think* this should be possible with a 5 psi setup, but I'm fairly certain it will be at 9 psi. SO... mostly I want to know if 9 psi would be a bad idea...
- Xanthos

Standard atmospheric pressure is 14 lbs. So adding 5 lbs of pressure is adding 35% more air, the more air: the more oxygen: the fuel can be burned: more power (it should put you around 400 hp at the crank). 9 lbs of boost = 64% more = just shy of 500 at the crank.

Intercoolers are needed because when you compress air it gets hot. Hot air is less dense (thats why hot air rises). The more boost you run, the hotter it gets. An intercooler cools the air back down increasing its density. And denser air has more oxygen which leads to more power. So there's the basics behind turbos and intercoolers (I think a post like this is needed ever few months on car forums)

Anyway, the V6 should be able to get you where you want with some minor bolt ons and other little upgrades. Plus, things like sticky tires are needed when you try and make the power you are looking at. so do that first and see how you do