5 GT Turbo 5 GT Turbo tuning advice

[Ash4ord]

Hello everyone

I am looking to purchase a phase 2, 5 GT turbo, As far as i am aware the engine is stock other than, S/S Carb Lobster,uprated Alloy Intercooler and air filter with a manual boost controller. I don't want crazy power i just want something relatively quick and reliable.

I was looking at cgbmotorsport's website just out of interest at their turbos where they state the following.

Turbo Technics Stage 2 T2/T25 Turbo


" We find many people purchase the biggest they can afford, rather than buying a turbo which suits there driving style."

63 exhaust housing for upto 200 BHP - full boost at 3500rpm - good 30-100+ mph
.47 exhaust housing for upto 185 BHP - full boost at 3000rpm - good 20-80 mph
.35 exhaust housing for upto 170 BHP - full boost at 2500rpm - good 0-60 mph

The above breakdown i found very insightful, 70+ Mph is of no interest to me what so ever as my younger days's of speeding are long gone. Im also not one to race off the lights or from a stand still i would say just a nice feeling of boost and pushed back into your seat action from 20-60 would keep me happy.

What would recommend a good spec to achieve this while keeping the car as reliable as possible?

Kind Regards

Ash.

 

[Ash4ord]

Will have a proper test run next time i take her out i when i get some dry weather. Im not in any rush to increase the power at the moment, no point really at this time of year but i am little egar to see what she would be like with a bit more power lol. I can imagine this car being awesome with more power.

 

[Mark Davis]

Haha the little tuning seed is blossoming already. I told you it's nearly impossible to not play with these things.

 

[Ash4ord]

Haha the little tuning seed is blossoming already. I told you it's nearly impossible to not play with these things.

lmao. Mate i thought i had out grown this stuff but this car has made me feel 18 again , The only thing i can be sure of is that i will be doing everything properly. This is possibly the most fun car i've ever owned, Sure its not the fastest, best handling, most comfy, best built but i honestly think its the most fun.

 

[Mark Davis]

Well once you get a bigger turbo, more boost, better suspension etc etc you'll be surprised how capable the little C1J engine is. 200hp + in a little lightweight 5 is good fun. Mad to think some people have replaced the C1J for other engines and running 400hp plus.

 

[Ash4ord]

How much power can the standard engine and gear box take before you need to start upgrading the internals?

 

[Mark Davis]

250ish I believe.

 

[Ash4ord]

WOW that's a lot of power for an old 1400.

Did these car's come with oil coolers as standard? just removed my front bumper to find one hiding behind it.#
Also are the front bumpers made out of fiberglass? mine currently has a fiberglass one, i'm not sure if its original

 

[andybond]

Did these car's come with oil coolers as standard? just removed my front bumper to find one hiding behind it.#

As part of the radiators setup , yes. Not a separate entity though.

Also are the front bumpers made out of fiberglass? mine currently has a fiberglass one, i'm not sure if its original

Sounds like a copy to me.

 

[DaveL485]

WOW that's a lot of power for an old 1400.

Yeah and when you realise Glenn's record was around 340hp without gas and 430-odd with, you start to wonder if he actually breached the laws of physics!

 

[Ash4ord]

That boggles the mind how such an old engine so small can produce that kind of power without braking. iirrc even in its day these engines where considered pretty ancient design wise weren't they? is this a case of good old fashioned over engineering?

Right i think its time for me to start playing with the boost and setting up the carb already, not had the car long lol!

So if i have got this right the standard T2 can only do 14psi before it starts pretty much blowing hot air, Do i need to turn up my boost to 14psi and then record my AFR reading throughout the entire rev range in 4th? Will you guy's then be able to tell me the most logical adjustments needed to tweak the carb from the results?

Also is it safe for the engine to do these test runs or is it better to adjust the carb first?

 

[Mark Davis]

I think from your previous posts at around 10psi you said you were seeing mid to high 11s in 4th WOT? If so I'd guess that if you raised to 14psi it would be too lean. Someone will be along to confirm I'm sure.

All I did was ask people who were running the boost that I wanted to run (20psi) what carb specs they had and then drilled mine (had mine drilled) to match. Most people make Ac Jet smaller or 2nd stage jet bigger for more fuel. A bit of trial and error really.

 

[Ash4ord]

Is it best to start adjusting the AC or 2nd stage 1st?

I am also thinking if i'm going to be playing with the carb why not just upgrade the turbo while im at it, I know i want the car quicker now, how much quicker is 4 psi going to noticeably feel is it a big jump from 10 or not so much? if the latter i may as well upgrade the turbo.

If i upgrade the turbo its looking like it will be the Turbo Technics Stage 2 T2/T25 from CGB im guessing .47 rear will be best for fast road use? Their site says 185 BHP - full boost at 3000rpm - good 20-80 mph.

What Psi should i shoot for with that turbo?

 

[Mark Davis]

I'm no expert on turbos, someone else can advise on that. I just bought a big turbo,

14psi should feel a bit quicker yes, probably around 140/150hp mark.

Standard carb is;
1.2mm main jet
1.25 air corrector
1mm 1st stage
1mm 2nd stage
0.45 idle jet
0.40 accelerator pump jet
1.7mm valve

For 20psi, mine has 0.85 ac and 1.3 2nd stage. The rest is standard.

 

[davemaygtt]

I got my 5 with totally standard engine running standard boost and upgraded quite gradually. Went to 14 psi first, then to a t2/25 running about 16, pushed that up later to about 18 and then to a vnt running 16 at the moment.
I would not skip over the t2 running 14 psi, that is a seriously fun setup! Also you will find as you up the boost things may break under increased pressure as they are old so doing things gradually can be quite helpful.
I think Brigsy already said drill the 2nd stage slightly first and then up the boost, you never want it running lean.
Good luck with it all.

 

[Ash4ord]

Thinking about it it dose seem a bit of a shame to miss out the steps in between they are all part of the fun!. I also get to learn something along the way.

How much should i enlarge the 2nd stage for 14 psi on the T2? and how will this effect eventually running a larger turbo like a T2/T25 hybrid as i have read that the 2nd stage can't be soldered and re drilled again.

 

[Mark Davis]

At a half educated guess I would say 1.1/1.2mm for the 2nd stage if mine is 1.3 for higher boost.

 

[davemaygtt]

I'm no expert and most of the work on my car has been done by people with experience however from lurking for the last 10 years I would say for 14 psi as Mark said 1.2 second stage and then run and check. If it needs more or for when you get the hybrid look at reducing the air corrector down to 1mm or .9.

 

[Ash4ord]

I'm no expert and most of the work on my car has been done by people with experience however from lurking for the last 10 years I would say for 14 psi as Mark said 1.2 second stage and then run and check. If it needs more or for when you get the hybrid look at reducing the air corrector down to 1mm or .9.

Cheers mate ill wait for somebody else to confirm and be sure.

If you do crack the clear part I may have a good one somewhere that I removed years ago but do be very careful and take your time.

Don't suppose you still have this mate? who ever put the metal face inside stuck plastic surround back on good and proper there was no way it was coming of without cracking

 

[Mark Davis]

My personal opinion on the power front is that eventually you get used to it and dare I say bored with it. I took the philosophy of going large from the get go to the point where I'm near the limit of what a carb can achieve. The final step can then be things such as handling.

I guess it depends what you want to achieve but 2 weeks ago you weren't going to change anything, now you want to go a bit further. When does it stop ?? haha

It's all good fun messing about with them though.

 

[Ash4ord]

It was the same with my last turbo car, Saab 9-5 aero early 230hp model, when i first got the car it felt quick, not long after i wanted more power, had it mapped felt a bit quicker but wanted more ended up at stage 3 which iirc was around 285 bhp with bags of torque. At stage 3 i was finally happy with the car, i ran it at stage 3 for a good 12 months and it always made me smile if i booted it in 2nd and 3rd.

Would of have liked more power, of course lol but i was very happy with it at that point, I love the Renault 5 as it is now, its fun to drive and very nippy, but i feel it would be truly AWESOME with more power.