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.

 

[Mark Davis]

The thing is with second and third gear acceleration is the fact you'll be into license losing speeds especially by the time you are up into third.

 

[Ash4ord]

Not on NSL road's twisties, I have some great twisty roads local to me where i can stay in 3rd/4th gear for miles without going over 70.

 

[andybond]

That's fair enough mate, makes sense. Good news that that's Clarkeys turbo, at least you know it's legit.

And me.

Buy it , and buy it now. If its good enough for Clarkey , it will be good enough for you.

@Clarkey is also a member on here so might be worth messaging him direct

 

[Ash4ord]

Spoken to clarkey via ebay, he said on his set up he gets full boost around 3750 Rpm, Im not sure if this would be too high for me especially with a standard cam that might result in quite a narrow power band.

On another note, i ran my car at 14psi to see what AFR's i was getting, 2nd and 3rd gear high 11's up to around 5k rpm where i stopped, 4th gear i'm a little unsure of, up to around 3.5k rpm i saw 12.3 then from 4k onwards high 11's so i m a little confused at these results, i have set it back to 10psi for now and need to investigate the jets in my current carb, I never really paid attention to rpm's when checking my AFR before but now back at 10psi, 4k rpm on wards in any gear is actually mid 11's, prior to 4k rpm i get high 11's which is where i noted my previous results from. So it seems at higher rpm's i get the lowest reading's. Is this normal?

I am beginning to think my current carb may have been played with. My car already had a wideband boss welded into the downpipe, it seems strange to go to the effort on installing one of those at some point to only run the car at 10psi. Some investigation needs to be done i think.

14 psi felt noticeably quicker, i noticed the tyres would screech a little in 2nd gear which didn't happen before in the dry, But this has also confirmed i definitely want a bigger turbo. How much power would you estimate a stock car to make at 14psi? im guessing around 130-140bhp? based on running the car at 14 psi, i think around 180bhp would be plenty.

 

[Mark Davis]

I test mine by checking at WOT in 3rd & 4th, taking it up to where I intend to rev it to. In my case off the clock but I am effectively making sure that I am around mid 11s as high up as I go in the rev range. I can't remember how it feels with a standard cam and turbo but I am guessing you are running out of puff around 5 - 5.5k ?

I ran my car for a short period with standard turbo running 14psi but with a 285 cam and the car felt horrible. As soon as I added the bigger turbo the car came alive but not until 4k plus, although since fitting front mount cooler it feels much more responsive in the lower rev range.

I think 140hp is roughly where you will be at that boost and spec.

There are a couple of Facebook groups that might be worth you joining, you tend to get quicker responses plus spare parts are found a little easier. I know of a chap in Bristol breaking a 5 and has a couple of known working carbs available. Failing that maybe send your new carb to one of the guys who can reburb and drill it for you. That way at least you know it is in good order rather than guessing.

 

[andybond]

Long pulls in 4th should really be used for the AFR.

 

[andybond]

im guessing around 130-140bhp?

Seems around right

think around 180bhp would be plenty.

Behave ! There is no such thing as enough power.

 

[Ash4ord]

Behave ! There is no such thing as enough power.

Yes but if we accept this reality we would never waste our time and money forever chasing an unattainable goal, The fun is in the chase

 

[andybond]

 

[Ash4ord]

Iv'e decided to just go for a T2/T25 hybrid with the .47 exhaust, Its looking like i will be ordering from CGB, unless anybody know's of any other places that are cheaper?

I messaged CGB and they told me The recommended maximum boost pressure for the turbo unit is 22 psi. What would you recommend i run it at? i'm guessing running it at the max 22 psi is not ideal.

And of course i then need to re jet my carb, Where should i start, drill the second stage and change the AC? if so what should size's should i start with?

 

[andybond]

You cant just rock on up and turn it upto 22 ! Even with the correct AFR the engine could be detonating.

You need to be really careful in the way you increase the boost or it will grenade on you.

 

[Ash4ord]

You cant just rock on up and turn it upto 22 ! Even with the correct AFR the engine could be detonating.

You need to be really careful in the way you increase the boost or it will grenade on you.

Thus why i asked what psi you recommend i run, what else do i need to do besides the fueling for correct afr's when running a larger turbo?

 

[andybond]

I cant tell you that buddy.

If you hit X Y or Z PSI it wont suddenly start knocking , different cars knock at different times. They arent always exact. You have to listen for it.

I bet it will be safe till 16 ish PSI if fuelling correctly , I wouldnt go much past that without det cans.

@Brigsy any advice ?

 

[andybond]

@Mart ?

 

[Ash4ord]

Ok my bad, for some reason i thought the t2/t25 route was the safe straight forward easy upgrade people did. Never heard of det can's but ill have a google.

 

[andybond]

Hehe !

I have general found when playing with the five is its easy , its trouble

 

[Ash4ord]

I thought it sounded to easy to be true.

 

[Ash4ord]

Any recommendations on det can's? What type of det can's do i need google comes up with all kinds, i assume ones that reach into the car? where do you attach them to the engine etc and how do you know what to listen for?

 

[andybond]

Any recommendations on det can's? What type of det can's do i need google comes up with all kinds, i assume ones that reach into the car? where do you attach them to the engine etc and how do you know what to listen for?

Where abouts are you ? Profile just says UK

 

[Ash4ord]

I'm in the midlands mate.