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Postby steveatyork » Fri Oct 07, 2005 4:14 pm

Maybe wrong :?: but there has been probs in the past using wrap on manifolds (more so cast) whith the wrap keeping the heat in and then causing them to crack :( "just info that i have been told" surly this could apply to a turbo :?: keeping the heat out of the engine bay "GOOD" but keeping it in the turbo "BAD" :?: :?:
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Postby clee » Fri Oct 07, 2005 4:20 pm

They would be more likely to crack if they had a sharp change of temperature ,the wrap would slow the cooling process so theoretically its better :? That's the reasoning behind running it for a few minutes to allow the oil to slowly dissipate the heat .The wrap will trap moisture tho so........................
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Postby David Gentleman » Fri Oct 07, 2005 5:19 pm

steveatyork wrote:im sure he can do a rear brace for less than £150 will find out tomoz,the exhaust housing is the exhaust side of the turbo which i am planning on changing so i can run a 3" exhaust pipe straight to it rather than it tappering down to a 21/2" as for the external wastegate all the big bhp japanese cars have them for better flow if its good enough for a skyline its good enough for an alpine just got to see if it fits :roll: ive been tolled that heat wrapping your turbo can be bad as its keeping the turbo hot when engine is turned off so its boiling the oil thats left in the turbo not sure how true this is just what some one had said to me


You don't have to go for a 3" downpipe Steve, as its all about back pressure, not just the diameter. Skylines/Cossies run 3" back systems because the system runs the whole length of the car, on a GTA its less than half the length, so 2.5" is sufficient.

Also there is no point having 3" out the back of the turbo, if your exhaust silencer/system is 2.5"....

As for heat wrap on a GTA, it is advised. Some cars have known to crack on cast manifolds and turbo, normally on 4 cylinder cars where it is right next to the head, and retains alot of heat. On a GTA, because of the tubular manifolds and the distance of the turbo away from the exhaust ports, alot of this heat is already lost in the length of the system, problem is its lost in the engine bay, and heats up alot of the intake piping - you may find your alloy boost hoses may absorb alot of ambient heat from the engine bay. Easy way to test is drive the car around for half hour without any boost, so there is no way the pipes can be heated up from within, and see how hot they get..
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Postby steveatyork » Fri Oct 07, 2005 6:56 pm

the bloke who made the exhaust said on turbo cars get the bore as big as possible as its all about getting gasses out as fast as you can,and the bloke who makes the alloy bits for me also builds zetec turbo escorts and he said in an ideal world i would have a 4" pipe coming of the turbo and sticking out of the wing but obviousley that would sound crap and probably set fire people walking past :lol: this is what i hate about tuning cars everybody has there own opinions and you get confused on which route to take :roll:
as for the cossie housings i know he deffo has a 63 cossie housing but not sure what the others are coz i had to get my dad to pick car up
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Postby David Gentleman » Fri Oct 07, 2005 7:30 pm

steveatyork wrote:the bloke who made the exhaust said on turbo cars get the bore as big as possible as its all about getting gasses out as fast as you can,and the bloke who makes the alloy bits for me also builds zetec turbo escorts and he said in an ideal world i would have a 4" pipe coming of the turbo and sticking out of the wing but obviousley that would sound crap and probably set fire people walking past :lol: this is what i hate about tuning cars everybody has there own opinions and you get confused on which route to take :roll:
as for the cossie housings i know he deffo has a 63 cossie housing but not sure what the others are coz i had to get my dad to pick car up


No, the practice is get the bore as big as REQUIRED. If there is no restriction using 2.5", then there is no need having 3", hell, if your going to have 4" you might as well have no exhaust at all and just have it coming straight out the back of the turbo. Its the simple law of diminishing returns.

What you also have to remember, is there is no real gain having a exhaust downpipe area larger than the combined area of the turbine wheel and wastegate port. I have a friend with a 700 odd hundred Supra, and he has had gains running a 4" straight through system, but only because of the length of the exhaust system, and the turbo he is running has a 3.2" turbine wheel, which is huge.

The GTA runs a 60mm turbine wheel and 22mm wastegate port, so its a bit of a different scenario.

Not being big headed, but I find alot of people in this industry say what should be done, but they don't know the technical reasons of what makes it work, and how and when these practices should be implemented.

..but thats my opionionion :D :D
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Postby steveatyork » Fri Oct 07, 2005 8:18 pm

Also there is no point having 3" out the back of the turbo, if your exhaust silencer/system is 2.5"....

3" Turbo back 2.5" X 2 = 5" into 3" tails = 6" :)
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Postby David Gentleman » Fri Oct 07, 2005 8:50 pm

hee hee....

3" area = 3/2 = 1.5 x 1.5 x 3.14 = 7.065 sq.in

2 x 2.5" area = 2.5/2 - 1.25 x 1.25 x 3.14 x 2 = 9.8 sq.in

..but your 3" downpipe will narrow down to 1 lot of 2.5", in order for it to split off.... :) :wink:
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Postby steveatyork » Fri Oct 07, 2005 10:24 pm

..but your 3" downpipe will narrow down to 1 lot of 2.5", in order for it to split off....

:?: Dont think it does Dave, 3" pipe straight into a middle chamber in the silencer then into 2 1/2" pipes either side into a chamber then into 3" tails, ill get some pics tomoz and email them over.

just collected it tonight, got my dad to drive it back, told him not to boot it, guess what he did :twisted: looked really impresive though lighting up the tail pipes between gear changes on full boost :D He still reckons theres a bit of catching up to do with his 450bhp+ RX7 :( (Single HKS Turbo) you never know Dave ime hopping that you will come up with some big BHP mods :)
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Postby David Gentleman » Fri Oct 07, 2005 10:59 pm

steveatyork wrote: ..in the silencer..


..you wot?.. :lol:

Truthfully Steve, to get big big power, you have to change absolutely everything.

New manifolds with twin T3 turbos - seperate exhausts and straight through silencers
In line chargecooler for each bank
High lift cam shafts
Engine management - 387cc Injectors
Atmo Weber style inlet manifolds with triple 45mm throttle bodies

..and then you have to decide to do all that to the 2.5, or upgrade to the 3.0 short engine, which has bigger capacity, lower compression, bigger inlet and exhaust valves and bigger inlet ports.

The A610 Lemans engine had the spec above and made 430bhp at 1bar, and 390lb of torque.
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Postby peterg » Fri Oct 07, 2005 11:44 pm

Steve, I think youve got to be realistic.....the factory tuners only acheived 280bhp on the standard engine, obviously the programmable ECU will release a few more BHP (with the cams that you havent yet got!) but 400 is a dream. Apart from that, the standard braking system is sh*t and will need upgrading beyond the current limits. What youve got to remember is that the GTA is a hell of a lot lighter than any of the japanese cars you want to keep up with....but if youre after ultimate power then youre barking up the wrong tree and you should give up now before you spend even more money. The GTA is an old car that handle reasnobly well and has a good dollop of torque but if you want to out drag Evo 8's at the traffic lights you'll need 1000's and 1000's of pounds.
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Postby steveatyork » Sat Oct 08, 2005 7:28 am

just collected it tonight, got my dad to drive it back, told him not to boot it, guess what he did looked really impresive though lighting up the tail pipes between gear changes on full boost He still reckons theres a bit of catching up to do with his 450bhp+ RX7 (Single HKS Turbo) you never know Dave ime hopping that you will come up with some big BHP mods

Note: it wasnt me that said 450+ lol think it was my dad been funny :D he has nothing but praise for the GTA and openly admits it is a much nicer car to drive then the RX7 and is pure exotic (OK Semi) compared to the japanese stuff)
The ECU will do me nicly and hopfully with some fine tuning around 280ish, It would be nice though to have a big power GTA, The RX7 has had £££££££££££££spent on it in Japan (Re-Amemia) and is well scary, but with £3000 re-builds every ???? expensive :!:

When talking about every ones diferent re; ideas on tuning ect, i mentioned the idea on covering the HKS T04 Turbo on the RX7 to the older one :) he had already asked the "best" RX7 specialist in the UK about this and the answer was a NO NO, every one as there own ideas :(
The rotary engine's run very HOT :evil:
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Postby David Gentleman » Sat Oct 08, 2005 12:48 pm

Another thing when comparing power figures, is alot of Japanese cars make lots of power simply through revs. An Rx7, Skyline can make 400 odd bhp but at around 8-9000rpm.

The best GTAs can make around 300bhp but peaking around 5000rpm, which is lots of power for such a low revs. If you look at the Rx power at these revs it would be way below this. Its a different style of power delivery.

That A610 Lemans, may have made 430bhp, but it was only at 6000rpm, which is a hell of alot of grunt.

The 21 Superproduction, which was only 2l and one turbo made 450bhp, but it had to use 8000rpm's to do it.
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Postby David Gentleman » Sat Oct 08, 2005 1:50 pm

steveatyork wrote:
When talking about every ones diferent re; ideas on tuning ect, i mentioned the idea on covering the HKS T04 Turbo on the RX7 and he said NO,NO.. :


But ask if he would do it if the Rx7 had the engine in back, with no airflow and poor intercooling/high charge temps and suffered component failure due to excessive engine bay temps....

Like I said, you have to assess every different application, there are no set rules. :D
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Postby steveatyork » Sat Oct 08, 2005 2:20 pm

so would the cry02 kit be a good investment on an alpine because you can get them from america for £200 £460 in the uk :(
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Postby David Gentleman » Sat Oct 08, 2005 2:52 pm

Id probably say better to go for water injection or a decent chargecooler system first.

Ive got some super compact cylindrical chargecoolers coming in which will be pretty cheap, and can be fitted anywhere, and still retain the factory intercooler as well.
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