What sort of rpm does a gt35 come on song on a 2 litre 4 pot engine?

 

On the escos' first engine we tried a gt35.82
The engine spec was a wrc 2.0l bottom end with big port big cam barrel throttle top end.
It would be making ok boost at 3500rpm with full boost around 4k. But couldnt pull it due to surge. It would then surge its nuts off till around 5500 and go like hell till 8500!
We put a ported shroud on it, whist stopped the surge. Whilst doing that it stopped it making full boost till 5500 lol!
IMO (<main thing here others may like them...) they're useless and are million times better turbos on the market.
We done to engine with them, one 600bhp when 600 was illusive and nothing else was available. And the one above which we took off..

 

M.a.d get good results with no surge talk to ade or rod they have both used them

 

Mad did mine and it like jimbos made boost around 3500rpm and full boost was around 4k

But mine didn't surge It just flew

I was on a yb with standard compression, fully worked head and custom grind cams, sm2 ecu and Siemens 83lbs

 

A GT35 is a reasonable turbo but it doesn't work well unless the engine spec is right for it and there needs to be a understanding on why/what causes surge to be able to spec a engine that works well with one and able to run full boost with no capping of it.

Mark

 

Hi mark
Why would you change a engine spec which you want to do the job when the turbo isn't upto it?
We wanted the engine to make full boost by 4k peak at 8k and be able to hold its power till 8.5 or higher.
The engine was amazing the turbo was useless on this spec we wanted/needed for the car. (150mph gearing at 8k so needed a little extra for the long straights..)
Put a t04z on it and it made full boost at 4.2k revved to 9k and made 40bhp more without a whisper of surge. No need for the compromise in this case.
I have no doubt you can make a gt35 work but I don't think it suits what we do with the yb as you have a very different outlook on them and they work with the specs you like
Unfortunately for the guys out there who may not be putting it onto a engine completely specced for it, your going to have a horrendous time IMHO!

Jim

 

Or was the gt35 amazing and your engine useless as it couldn't consume the air being forced in? Only joking but it does serve as what ideally is needed is to match the overall spec. No engine/turbo can be useless, it just didn't meet your requirements.

Just to be awkward....do you not class your 200rpm over target threshold as a compromise?
Did you try capping the 35 back til 4.2k and checking for surge?

 

One would argue that putting a 7lb air bigger turbo should make it surge more in that case?

If you read my post you will find it surges from 4k where it would allow full boost other than the surge all the way till 5k

I also beleive that a turbo and particularly an engine can be useless. (without being silly..)

 

I don't need to change my spec as it works on a GT35, I would have expected more from a T04Z over a GT35,
If we are talking about other turbo's then the BW turbo is the better one anyway.

Mark

 

I think you've mis understood me mark Im talking solely about surge, this was four years ago
Your spec may well be fine for you but if I came to you as a customer with a built car wanting an engine to rev to over 8500 would you have chooses a gt35? As I don't personally think the cams needed to achieve the power at those rpms allow a gt35 to work well.

 

I would choose a BW turbo over just about any Garrett turbo.

Mark

 

So changing only the cover itself, from normal to ported meant full boost took over 1000rpm later to achieve ??

Same boost level ?

 

Yes that's correct, it stopped it acheiving full boost untill 5500, well 5300 would prob be about right i dont think it was wuite 5500.
we actually took it back off as on the boost map we could cap it to get the best possible.
27 @ 4k sloping in to 33psi by 5300rpm

It was quite surprising to us aswell steve as on the gt30 it didn't make such a huge difference but the 35 it was huge.