Right my car has finally been mapped by AndyF
Spec 2.5 CDB,Lateral GT3040 turbo,800cc Sards, and other supporting mods.
Car seems to be a bit laggy and it sings once in full chat.

But i do have a question or 2.

1. When should you see 1 bar of boost in 4th gear?
2. How can i improve spool up?
3. What size is the exhaust housing on a GT3040 and can i improve spool up by fitting a smaller housing?

I probably have more questions but just no time to think about them.

Power is +500/+500 without RR yet.

 

You should really ask Andy mate. You won't get much more knowledgeable than him and he knows how your car is behaving on the current set up intimately.

Sounds like you're running a monster turbo, so it's probably never gonna be great in terms of spool, even on a 2.5!

Ns04

 

having huge power, there will always be a trade off in spool up.

 

I would check with the company who supplied the turbo to know what size the exhaust housing as they can be changed iirc normally they come with a 0.82 ex housing.

I am using the 0.63 housing on my gt30R and seeing 1 bar before 3000 rpm in 4th.

My brother is running the same turbo setup on a 2.5 sti8 with avcs & equal length headers and is seeing 1 bar just over 2600 rpm.

Yours should spool up slightly later due to the slightly larger compressor wheel in the 3040

I think droping the ex a/r down from a 0.82 to 0.63 will spool up 400-500 rpm earlier, but as per above post will then limit the top end power. Also probably need a remap aswell.

 

Well i don't get 1 bar till 3900rpm in 4th on STI 8 type UK

That sucks....maybe need to look at new headers

 

Fail7,
That don't sound great I must admit.

I can't remember what mine does in 4th, but in 5th/6th it reaches 1bar at 3k. This is obviously on a 6sp box, standard position AET Hybrid GT30 (using the largest available GT30 core), larger compressor housing and a .63 exh. housing. I am also using twin scroll tubular headers (standard) and a modified twin to single scroll up-pipe. To top this off, my Cosworth engine has Cossie Big Heads (which in affect could hamper lowdown driveability if anything, but give me better gains at the top end) and Cossie Race CAMS.

I would hate to say what would specifically help with spool-up of your build, as my build is about the complete package and not one individual item really.

Obvious initial choice for you, would be a smaller exhaust housing (if you are already on a .82). I have no idea what size compressor wheel you have, so can not comment (in relation to mine), but mine is the largest available (so that probably wont help lol).

I must admit, I do think that turbo spool up is not the be all and end all, for straight comparison purposes (unless you are comparing same turbo spec, like for like). Ok, it's better to have it sooner etc, but I am making less boost early on when compared to my 2ltr twin scroll set-up. The original set-up produced 1bar at 2600rpm. Now this turbo I have on now is huge compared to the old one, but it making less boost early on, but is making a shedload more power / torque everywhere!!

I suppose I am trying to say that boost is relational to the turbo etc, and should not be a direct comparator. When I am getting more power / torque throughout THE WHOLE rev range now, why should I be concerned if the set-up only produces x psi at y rpm, compared to my previous set-up.

If I had the same boost spool on this set-up as my previous set-up, based on the power / torque it produces at the psi now, the car would take off to the moon.

Regards,
Shaun

 

How much boost are you running and when do you see full boost. 1bar by 3900rpm doesn't leave you many revs to play with. Definitely chat to Andy and find out what his take on it is ... I am sure he will offer some suggestions.

 

rearrange the following words

long string is how a of piece

Now speak to Andy, given there are far too many variables even on a Turbo, irrespective of other variables that the car has to make the answer a waste of time

 

car runs 2 ar @ 4500 or there about and hold that till 7500

I did email him but he must be busy as i have not heard back from him yet.

 

Thanks for some info Shaun

 

np

 

I think if your on VVT heads you should see full boost by 3800rpm ?? mine was a gt3076 and on sti5 heads it was making full boost at 4200rpm and thats on the same 2.5ltr engine

 

I hope so too Steve but will get it looked at soon.

Just ran a 11.08 @ 132mph today at Crail.... :-)

 

roflol

Stop worrying about your boost profile then!!!!

 

My full boost is at 4200 to 4300 but i would like to see it coimg on further down the rev range as i've been told that 1 bar should be at 3000rpm.

What size of up pipe are you using Steve.

To make a good comparsion i need someone with the same turbo and similar engine.

 

I'm just greedy and want the best of both worlds