Can Nitrous help aid with small turbocharger top end ~~

Hey guys how are your evenings & Happy 4th!
Hope everyone has also had as much coffee as i had this morning too

conclusion:

SO could it be possible to use a certain amount of Nitrous shot triggered by megasquirt only under the conditions of MAP > 196KPA AND RPM > 5900 to make the goal of 330 maybe even 340whp out of a GT2554R(for time attack)? Has anyone ever attempted this before?

I don't want to do it if it would be bad for the turbo. What would happen, what should i be worried about if going thru with this? Thanks

Also running a 2.5" flyin miata down pipe and full 3" catless exhaust. But oem 1995 intake manifold and cast iron log manifold.

intro:

1.8l BP from a 95 stock bottom end.
I have plans to eventually rebuild with forged connecting rods. Currently running E85 on a Garrett GT2554R turbocharger. Right now she makes 270 whp all day (dynojet numbers) using virtual dyno. With a really nice flat torque curve across the rev range using electronic boost control. Starts at 11psi down low and tapers up to 14 to 15.5psi at redline. Torque stays between 215-222wtq all the way across.

The car is great for autocross and street. I am in love with the current setup. But with future plans of always wanting to do road course track days and time attack, I'm focused on seeing if i can get more top end with a built engine and 6 speed. Perhaps a power goal of 330whp.

I know the traditional tried and true way is to go large turbo and use nitrous as a spool aid down low if necessary. But i just purchased the GT2554R and it's 4/5ths paid off. Yes financed. Would really rather not change turbos if i don't have to.

So my theory and thinking is the choke point is around 280whp and beyond the turbo is already pushing out of the range of efficiency. I do have a large intercooler and running e85. I have my IAT sensor threaded right about 10" down from the throttle body and I've never seen more than 110°f somehow. Doesn't matter how hot out it is or how many pulls, it's always between 90-108°f usually. I've been pretty surprised about that. Even with the old large china charger i used to run, the IAT's stayed the same after changing to the Garrett.

Apologises for the mouthful

 

I think that if you're financing a turbo on a 25 year old car that isn't earning you money winning races, it's high time to stop spending money.

I also think that the logic of going to a bigger turbo to accomplish bigger turbo goals doesn't change just because you still owe money on your small turbo. Are you afraid that you wouldn't have the title in hand when you go to sell your 2554?

 

Not sure where to start here.

you want to run turbo and nitrous on a stock motor, race it, and your finances turbo isn’t paid off?

just doesn’t seem like a good way to go..

 

Guys i appreciate your concerns for me personally. Apologies for making the post come across as being personal. I just meant to get as much of the back story out of the way up front in the first post instead of later on.

the question I'm asking is

Can Nitrous + GT2554r = 330-340whp?? (Safely)

would this do harm to the turbo, or engine or what is the problem with doing this? What's the science and factual issues? Something doesn't seem right to me about doing it but it also sounds like it could work.

(assuming the engine is running forged connecting rods, e85, big intercooler, cast manifold and the nitrous is only for after 5800RPM & 14psi of boost)

can this be a good time attack build?

 

Yes it will help you reach your power goal. Yes it will harm your engine if your comparing a non-nitrous car to one with nitrous. It's all about cylinder pressure, which goes up exponentially with nitrous. First look over your rule books. I remember seeing it banned with most road racing organizations. Also if your trying to compare money, sell your turbo for the correct size asap and take your $500 hit on the chin. Nitrous will end up costing you far more in just consumables with even 1 20minute session.

 

I think this is a bad idea since the whole setup will be choked by the small turbine. I guess the E-MAP will go very high causing an inefficient combination: more heat and cylinder pressure compared to making the same power with a bigger turbo.

 

340 rwhp of horsepower means 340 rwhp of exhaust gasses produced that need to flow out of the engine through either the turbine or the wastegate. I suspect the wastegate isn't big enough to bypass that much flow and you're going to wind up with boost spikes at the very least, and quite possibly overspinning the turbine wheel and blowing it up.

I agree that you'll be better off using the money you would have spent on nitrous to upgrade to a bigger turbo system.

The one combo I've heard of for nitrous and turbos in road racing is the opposite to what you're proposing -- where a small amount of nitrous is used for spooling up a big turbo below the RPM at which the engine could normally do it. This is practical because the very limited amount of use means that it's possible to carry enough to last a while.

--Ian

 

Thank you That's exactly what my train of thought was. So far that's what i thought would be the only issue. So to ghetto rig a fix for it, would be to use *two* wastegates. The internal wategate has the electronic boost controls. Which can manage up to 14psi max. Then an external wastegate (using no boost control) could be installed on the cast iron log manifold and have a 15psi spring. The external wategate dump pipe recirculates the gasses around the turbine housing back to the down pipe.
it would take some tuning between the two gates to find a way to get it to work but that should be able to prevent from overspinning and overboosting. Then we continue with any other possible problems?
i don't think there are any. I think it would work lol.
I was hoping it would work without needing an external wastegate though

This should help with preventing the turbine from overspinning.

 

Oh and for who else pointed out that nitrous might not even be allowed in the time attack organization i find, thank you i completely forgot about that. So i really don't know if i would do it when that becomes the case. But it still seems like a cool way to get more power out of an existing setup.

 

Make a post on your instagram and ask

 

And how much time will it take to modify and install this second wastegate let alone trying to tune them to do what you want without destroying your financed turbo or ventilating the block with broken rods?

STOP, build the engine first (oh wait, maybe you can't until you pay off the turbo), upgrade the turbo next, and reverse your nitrous thinking. A smaller shot down low is much better than your wild idea. If it were a marginal idea you'd find discussion or build threads online but without searching I'd say there aren't any because it's not worth trying to bypassing the turbo and run nitrous at high RPM.

 

I have ran nitrous on a 2 litre 16v turbo combination (Ford) where the turbo was close to flat out and the nitrous was added on top across the whole rev range. It played out as described above although we did not measure manifold back pressure.

It gave a great bump in low down power, lowered the boost threshold RPM but then the power gain tailed off towards the top end. It was a c310WHP turbo only - made an extra 75WHP in the mid and an extra 40WHP at top. The top end power was no greater than a similar engine/turbo combo being pushed on max kill with no nitrous. Most likely the top end reduction in gain was exhaust back pressure. Turbo was internal wastegate.

It was a long time ago (c.20 years) but I think there was also some playing about with the wastegate control and again this was probably due to increased back pressure.