Thread: With regards to Turbo VE's

feel free to skip to the last paragraph to get to point faster, I know long posts are hard to read.


What really works for power when the VE motor is turbo-charged? I have started off small and made some progress in my journey for big numbers, but something isn't right. I have made decent numbers, but not great numbers. The revelation came to me today after riding in a civic hatch turbo with a b18c1 swap. The thing was built, turbo, and tuned right. The Vtech hit and hit really hard. The vtech was very audible on this motor. It makes me feel bad though because ever since I went turbo on my VVL I have not been able to hear the vvl switchover.

My last dyno was at 10psi, I made 260whp. Without cams switching. But when the cams switch, I lost 10whp. How can that be? how do the cams make me lose power?

Not many people go turbo with these engines, but someone here has to have some insight on why the cams don't make power like they should.

The turbo used is a gt3076r .63 ar housing. And this is my thought.

I had stock cam gears before, stock timing. I got some cam gears to help take out some overlap, but is this necessary? Should I upgrade the housing to a .82 ar to improve flow and reduce backpressure?

I think I may be on the right track by saying that reversion is happening because of the restrictive exhaust housing, and the valve overlap just makes the problem worse.

Without being too long winded and hard to read, does anyone have an idea of what is happening when my cams switch? Stock sr20ve cams, gt3076r .63 ar, but I am losing power when the cams switch... Can this be solved with cam timing? or will a bigger AR housing get better results?

Well I have a friend with a B18c1 motor on boost and he has his VTEC set a 6,500, reason why is when the powerband is about to die the VTEC engages to maintain the powerband, most ppl think that the sooner the VTEC or VVL activates the more power they should make.

I think you should dyno the car without VVL being activated and see where the powerband drops, then set the vvl activation point 200 rpm sooner

just my thoughts.

The problem is not that I am losing power without the cams. I can switch them at 7k and I still lose power. The only thing I can think of is the log mani +.63 ar + tons of overlap=loss of power.

Maybe I should try -5 +5 on the cams to dial out the overlap? Andreas has mentioned this before when using the sr16ve cams. I just don't know what I should try first. All the honda guys around here are running huge ar housings and making a ton of power. But I am scared of the car being too laggy for my track sessions.

I don't know how the VVL will respond to the bigger .82 housing. I have been reading threads on honda-tech and rsxclub forums to see what they are doing, but I am tired of searching and searching. Seems like everyone keeps this info closely guarded tuning secrets.

power on small cams seems to level out at about 7k.

After talking with some honda guys, their secret is equal length manifolds with long runners and a big housing. This is good for top end power production, but they say their cars are laggy until they get going.

I am leaning towards keeping the smaller housing and trying to make good useable power in the midrange. I don't want to have to rev the VE to 9000rpm to make a good powerband.

So I am upgrading my 300hp intercooler to a much much bigger unit and taking out as much overlap as reasonable to start. Andre says with sr16 cams maybe -5 +5, so maybe I will start there. We will see what that does. If you guys need a guinnea pig I am gonna be it. I wanna really find out what it takes to fix this problem.

Where is rawkus when you need him?

Did you have your pistons fly cut for 16VE valve reliefs?

We have done a few turbo SR2-VE and we just use the J&E DET piston they sell either 8 to 1 or 8.5 to 1, which is 8.8 to 1 or 9.3 to 1 in a VE and they do not have valve notches and we never had any valves touch.

i definitly wouldnt go with a setup that is more for drag and makes all its power at top end. i would go with either a larger housing with a log manifold or a smaller housing with a equal length manifold, but definitly would look into exactly how the manifold is going to effect the spool, and the powerband.

i am runnnig a gt2871r with a .86ar housing and log manifold and i think its a very nice combo the boost isnt laggy and i think that has to do with the log manifold not being over the top to extend that lag that normally you would see with a equal length manifold and larger AR.

i think you have it good tho, go with something like a equal length manifold and smaller ar so you see better spool and midrange powerband

Even with 16VE cams and cam gears set to 5,5?

Buying a new mani is prolly out. The log design flows good and is dead reliable. The JE pistons are a great set, but I havn't seen an 8.0:1 compression. The ones I have in there now have huge valve reliefs cut into them. If they have some 8:1 available that is what I will go with. I was thinking of having the 8.5:1 compression pistons cut down a little to a bigger dish to lower compression ratio. 8.8 is perfect.

The difference between the t2 flange .82 and the t3 flange. .82 I hear is pretty big for my turbo. But I am willing to try anything on sound advice. Some people tell me the bigger ar will shift the power up in the rev range and I don't need that. I want these cams to max out at 7500rpm. I don't want the power to just keep climbing necessitating more revs.