Thread: 20V vs N1 turbo comparo blabbery

congrats getting the 20v vs n1 deathmatch on. In for results

I wonder if there is a 3rd horse here - 2 20v intake cams. has it been done, is there a thread? i haven't run across it yet but i'm pretty noob.




fwiw i'm running 11 3/4" rotor with 15" wheels (sorry on miata so not a bolt on for u). not cheap (900) but cheap consumables make up for it.

Thanks for the info.



I seriously hope you don't think that exhaust pressure is ever over plenum pressure with a boosted application.

Walker

Are you asking me if I think exhaust manifold pressure ever gets above your boost pressure?

If so your darn right it can and will with a restrictive setup. T2's for example will do this especially when you over boost them. T2's on a VE is a prime example. Small housing T3's on a log manifold will do this. Yes you dont want exhaust pressure to be higher than boost pressure. 1:1 is optimal. Ask any big honda builder thats making 1000+whp, running 45-50lbs of boost whether they want higher than boost exhaust pressures.

I looked at the logs of Tony Palos R35 GTR and it was runnin I believe 29 lbs of boost on some T2's and exhaust pressures were up near 59psi up top. He said thats how you know when your out of turbo flow on the exhaust side.

Ive seen many many logs of high hp hondas, On Big 72mm BW's with the smaller housings these guys were seeing about 52psi of exhaust pressure vs 45psi of Boost pressure and still complaining. Went to the larger turbine housing to fix the issue. They complain because it can cause issue with the massive cams with a good amount of overlap that they use on their cars. Its no secret.

This is why i thouroughly believe that the n1's in this case with coheeds new setup will outperform the 20v's and why for my setup i chose the n1's over the 16ve's I was originally going to run. Guess we will see if my predictions prove to be right soon enough.

Ashton, I cannot help you. We will both be awaiting the results.

Walker

On most boosted setups backpressure>boost. Until you go with a large turbo with a free-flowing turbine. On bigger turbos you can get crossover, and can take advantage of the overlap. But too much overlap can be bad if boost is excessively more than backpressure. You see what happens in this situation in supercharged vehicles. The overlap causes the air/fuel mix to go right out the exhaust.

On my setup Im actually going to be logging backpressure so you will get to see first hand the relation to boost and backpressure on an efficient turbo setup, large runner equal length t4 manifold and large t4 turbine housing on a large turbo.

One thing I can tell you about runner size is, it has a huge affect on exhaust velocity or speed. The runner size you use really depends on the a/r size of the turbine housing, and when you want boost. You can really change the boost/power characteristics of a motor with these two variables. If this discussion was n/a, there would actually be a correct answer.

My runners are using SCH40 pipe, 1.5" iirc. Been a few years. But velocity is a bit quicker than a SCH10 because of the thicker pipe.

Long runners. About 21" long. I am interested to see how the N1 perform. One thing I really liked about the SR16 cams was the huge increase in power when the cams kicked. The surge was incredible, even part throttle. But the idle seemed erratic at times, and the bottom end power wasn't that great.

I really need to keep as much bottom end power as I can though. Cruising at freeway speeds at 3k rpm requires some power to keep it in 6th gear. The 20V do great in this department.

the SR16 cams seemed to lose all their steam after 8k as well with the GT3076r. But how they would react to the 6262 could be a different story. That's why this test is going to be so good. It will show the output of the different overlap profiles. the N1 is very close to the 1.6 in overlap, but has a bigger duration and 1mm more lift. It will be great to see how high rpm power delivery is. If the N1 beat out the 20V it will most likely be in the mid-range to 8k. The 20V I hope to show better low-cam power delivery.

It will be interesting to see what the car does on the dynojet in its current stage. After this cam test, I will have successfully tried all OEM cams available for the VE.

The only watch out with regard to big overlap on boosted engines that I've not seen mentioned in this discussion is whats commonly reffered to as "turbine chill". This is where the overlap on the cam causes un-combusted gas to enter the exhaust and reduce the exhaust gas temperatures; reducing the energy available to the turbine and hence increasing lag and reducing peak power.

I really hope you plan on adjusting cam timing, I think especially in your case it will make huge differences