Smaller Cooler Pipe Causing Power Loss?

[WYTSKY]

Hey guys,

Little while ago did a few dyno runs, we found that the car is still performing as she should power wise (280-285rwkw) but after a few runs power started dropping.

One thought of this is because the car seems to be getting quite hot, and the reason for the hotness is possibly because one part of my cooler piping might be causing a restriction.

Now interms of cooling, car is running standard radiator, large fmic and 2.5inch cooler piping except for this pipe shown below ( roughly 1.9-2inchs), car always stays between 78-81 at operating temp and max 85 on a hot day after some spirited driving, so I don't feel any of the radiator stuff is affecting it.

I will be inserting the pipe next to it into the system in the next few days, but just wanted to check if people may have thoughts/experiences of what could be causing a gradual power loss

Btw, I never put this in the system, roughly 2 years ago when I got my car back from a mechanic that i never would go to again, it came back with this adapter pipe.

[krzysiu]

What is your intake setup? Do you have a pod in the engine bay or have it enclosed with a CAI?

[ARTZ]

wouldn't be helping, just replace it and see if its better..

you could probably even replace it with a silicon hose bend in the correct size..

[R31Nismoid]

you wouldn't think that would do it... not id it makes the power straight up.

sounds like heat soak starting so as said above... airbox or pods?

also, what cooler setup?

have you tested inlet temps?

[GTScotT]

+1 suspected heat soak.

Changing that pipe would make it breath better that is a given, however I doubt the restriction would cause that much difference to power delivery.

First things first, check your cooler core for excessive oil residue and consider intake location/setup along with cooler quality.

[zebra]

This is a converted non turbo yeah?

Does it still have the NA radiator? It might be struggling with 280odd kws and only a dyno fan providing any airflow.

[tridentt150v]

Plus how long was it between runs, your tyres could be slipping a tad as well.

[WYTSKY]

I have my own custom heatshield and CAI for the pod - some of you may have seen it in the tutorial section - it definitely helps on hot days, pic attached.

I have not tested inlet temps, any non expensive device I could pick up from jaycar/or something alike that would do the job?

cooler setup - well it is a cheapy, its one of those hybrid copy ones that you get for about $300 incl piping - it seems to have done the job fine up until this bigger turbo setup, dont know when they reach their limits/restriction

i havent checked the core for excessive oil residue as i dont get any blow by or any blueish smoke, i will check it this wkend though, why would that affect heat soak?

I never thought about the fact that it is an n/a radiator... ive never compared it to a turbo one so not sure on the differences

runs were back to back, but car was strapped.

Thanks for the thoughts guys

[R31Nismoid]

Oil ETC = restriction if there is a bit in the cooler.

Also heats up over time etc.

[75coupe]

could the afm being over the exhaust manifold area be a problem....

[Rolls]

Sounds like typical heat soak to me.

[WYTSKY]

Update: was busy this weekend so only managed to get it done tonight. I havent taken it for a long drive but gave it a few squirts up to the legal limit and I must say I am quite surprised at the difference, I thought there would be little to no difference but I genuinely feel there is more consistent power there even after doing it a few times.

Tomorrow driving to work and back will be a better test but after a substantial period of time like all cars things will get warm, whether there is a noticeable drop though will be what i am looking for.

I dont really have a great image of before and after, but I have circled what parts have changed below.

Before:

After:

[GTScotT]

OK, I have a theory......

Things I want to know:

Housing AR

Decomp mods?

Boost response RPMs

I bet your turbo spools nice and early... Not laggy at all. I have an odd suspicion that the DE+T compression has tipped your exhaust housing out of efficiency and boost delivery isnt optimal.

$10 bucks says your cooler is as good as everyone else running a china cooler whos doing OK.. And your actual issue is EGT transpiring to in cylinder temps.

JUST a thought, an expensive one to test too.

[WYTSKY]

Front Housing AR : .60

Rear Housing: .63

Cooler piping now all 2.5 inch

No decomp mods at all, just n/a with turbo strapped on

as for response: I have attached one of my latest sheets, just after we started loosing power (only 4 kw drop but got worse) but you can see, theres full boost - 18psi @ 3000rpm.... even at 2-3000 theres 9 psi to use, which is great for real street use. so your guessing of early spool is correct.

1 thing to add to your theory, I think, i stress I think, that i vaguely had this problem before too with the old hypergear turbo, but because power was alot lower it was only a few kw drop max... ie.. 230 was max... would maybe drop to 22(0/2)kw whereas now it can be 20kw+

[toffy]

what about oil temp/fuel temp etc? these would have an effect on consecutive runs?

[GTScotT]

I'm confident your exhaust housing is the problem mate.

Going to the bigger AR is not going to harm delivery, boost will come in later but road speed will increase. I know it sounds crazy, but by all theory the upped CR would be bringing the turbo in much earlier. The earlier the turbo comes in the earlier it maxes out.

By my theory, your turbo would be maxing out (flow wise) probably before 5000RPM. It still continues to make power but really inefficiently. Heat builds in the exhaust housing and soaks into the cylinder bore. Next thing you know your next strokes are MUCH harder to make the power with and it starts to drop off.

If you want to try and test this, try dropping the boost and see how consistent it is. I mean by dropping it down to about 10psi. See if you can get consistent run after run like that or how much better it is atleast.

18psi is an awful lot to be squeezing through a .63 rear end on a GT30 IMO. You may just be the unexpected pioneer to prove this theory right...

Your example of the highflow is perfectly relevant. The housing size is tiny on a highflow, they generally run out of puff really early. This is why you see Stao using large pitch turbine wheels to mitigate the issues of the small housing. Once the housing effectively runs out of puff the pitch in turbine blades allows enough exhaust gas to bleed as a bypass and the turbo can max out alot easier.

Remember we are dealing with shaft speed @ desired flow. Changing the exhaust AR changes the points at which you see certain shaft speeds, which will determine in effect how quickly we max the entire system out regardless of AR.

Theres just too much to get into and its too late and I need sleep. And and and and. Yep.

[WYTSKY]

what about oil temp/fuel temp etc? these would have an effect on consecutive runs?

hmmm, i havent thought about that, I dont have an oil cooler, does that help in this situation though, or is it only for real consistent hammering around a track?

I'm confident your exhaust housing is the problem mate.

Going to the bigger AR is not going to harm delivery, boost will come in later but road speed will increase. I know it sounds crazy, but by all theory the upped CR would be bringing the turbo in much earlier. The earlier the turbo comes in the earlier it maxes out.

By my theory, your turbo would be maxing out (flow wise) probably before 5000RPM. It still continues to make power but really inefficiently. Heat builds in the exhaust housing and soaks into the cylinder bore. Next thing you know your next strokes are MUCH harder to make the power with and it starts to drop off.

If you want to try and test this, try dropping the boost and see how consistent it is. I mean by dropping it down to about 10psi. See if you can get consistent run after run like that or how much better it is atleast.

18psi is an awful lot to be squeezing through a .63 rear end on a GT30 IMO. You may just be the unexpected pioneer to prove this theory right...

Your example of the highflow is perfectly relevant. The housing size is tiny on a highflow, they generally run out of puff really early. This is why you see Stao using large pitch turbine wheels to mitigate the issues of the small housing. Once the housing effectively runs out of puff the pitch in turbine blades allows enough exhaust gas to bleed as a bypass and the turbo can max out alot easier.

Remember we are dealing with shaft speed @ desired flow. Changing the exhaust AR changes the points at which you see certain shaft speeds, which will determine in effect how quickly we max the entire system out regardless of AR.

Theres just too much to get into and its too late and I need sleep. And and and and. Yep.

So the .82 rear housing is what you think will solve all this? if so it would be a bugger because I have just got the rear end of this nice with the gate on a perfect angle for my aircon line to be put back in + tuning is all done.

Can someone do some sort of porting on the rear housing to help a little or is that something else?

So in all you think its not my current cooling equipment/methods that are causing a problem, you think the turbo cannot expel air fast enough? just trying to make sure i understand the situation correctly.

Btw, the previous turbo was not a highflow, was one of the original tr43's i think, its rear actually seems longer/larger then my current turbo, i know it needed more room though for the iw.

[Harey]

I agree that its the 0.63 exhaust housing that is causing the drop up the very top.

The car has amazing response though! I reckon leave it as is and just change at 6,500ish. As everyone says how often are you above 6,500rpm compared to under it.

This would be a very fast road car. Yes you can spend a lot of cash changing over to 0.82 and while you will get more of a top end rush it will be slower overall on the street. My vote keep it and enjoy

Only worry would be if the temps are too high to be reliable.

[WYTSKY]

I agree that its the 0.63 exhaust housing that is causing the drop up the very top.

The car has amazing response though! I reckon leave it as is and just change at 6,500ish. As everyone says how often are you above 6,500rpm compared to under it.

This would be a very fast road car. Yes you can spend a lot of cash changing over to 0.82 and while you will get more of a top end rush it will be slower overall on the street. My vote keep it and enjoy

Only worry would be if the temps are too high to be reliable.

Oh dont get me wrong, love the way the car feels now, absolutely great on the road, every kw is useable, I just want to keep her cool to keep the power the same its just after driving in traffic for 45 mins shes feels at 260-270ishkw...

I wouldnt bother with a .82 housing for a long time... until i was bored of the current power, I just wanted to see what things I can do without changing parts of the turbo to be cooler.

[WYTSKY]

Another update:

Sorry to drag this out, but i do want to try to eliminate all possibilities and i have some more results from today.

Just got home, been in traffic for an hour and a half, was pretty warm, 24-26ish on the radio. Gave it a squirt just as I was getting home and it still is bad, big loss of power, I would have guessed more then 30kw loss.... opened the bonnet and checked everything temp wise with my hand....

my heat shield and pod were warm, the intercooler piping after the intercooler was warm as well, however all the intercooler piping BEFORE the intercooler ( including the part I have just changed) was really hot... couldnt keep my hand on it for more then a few seconds so I am definetly now convinced it is bad heatsoak.

The large metal intake pipe was hot aswell, so my cai + heatshield work for the pod inside, but as soon as the air gets past that it gets really hot.

I can tell all this heat is coming from the molten lava that is my exhaust manifold, so:

Edit: where is the best place to get heat wrap and what is the best brand?

What else can be done to keep the manifold heat away from the cooler pipes?

Also Scott, your theory may well be correct and adding to the problem too.