[batou]

Quote: Originally Posted by Snowie (original)

Batou
My GP is very driveable in all road conditions by both myself and my wife.

The only real problem is traction if you really boot it away from standstill.

Power and torque delivery is very smooth.

At WOT you realise how quickly you need to change gear

Alan

Sounds good, although I'd hate to be the guinea pig by having headwork on just a pulley'd car I'm still very interested. I would imagine being a better, stronger head you wouldn't worry as much about feeding it more power. Still interested to see what else needs changing at the same time or weather it's a straight swap, I imagine while the cars in bits it's probably worth going to town on it anyway lol .

Ant, I was at the same RR as snowie and heard his car first hand (when the battery had some life in it lol ) and put it this way, it honestly wouldn't have surprised me to see him loading it into a works rally team truck for the drive home from the way it sounds!!!!! It doesn't sound like a modded car, it sounds like a flipping race tuned car!!

[roland2003]

Thanks for the reveiw Alan........new GTT 'Pro Mapping' coming very soon.
41bhp on a customer car & proven using the same independant RR ....(with post head change air leak sorted) .
And superb acceleration test results, not stripped out, pump fuel, normal tyres & normal tyre pressures, no hidden mods...
Alans car is relativly quiet.,big valve heads & cams do add a little volume though ......fit a Borla exhaust to it and that would be loud!

[BigShow300]

Hi Roland

Just so I'm clear here as I'm worried I'm being a bit thick and from our conversation on heads you'll know I'm not the most knowledgeable in this area... Snowie started with 202 bhp as rock stock (Surrey RR) then added:

GTT + 3% crank
GTT Hybrid filter
GTT tensioner mod and pulleys
JCM 4-2-1 sports manifold and sports cat
GTT Stage 4 cylinder head
Shrick valves
Shrick high lift cam
AFPR
450cc injectors
Modified bypass valve
GTT - 15% SC pulley

And got 252 bhp (Surrey RR).

So its not just the adding of a stage 4 head that’s giving the power its a combination of all the parts listed??? My reason for asking is that I'm trying to predict what power I might achieve with the mods I have if I went for something like a stage 4 head. On paper it seems like I could achieve 15-20 bhp extra if it was just the head (inc valves, cam & injectors) or 20-30 bhp extra if it was the head plus modified bypass valve, AFPR & +3% crank giving a theoretical maximum BHP of about 260 in combination with the mods I have.

Does this sound right or am I going down completely the wrong route?? I know you've tried explaining it to others above but I'm still a bit cloudy .

[GT4 Baz]

Slightly off topic but back to the inetrcoolers.....

DOn't forget the larger IC's act as a heatsink so while you might not see a power gain over the GP one with a GRS over a few dyno runs, it does have a giher specific heat capacity. So over a period of high rev activity (on the track or a back road thrash), the larger GRS and GTT IC's will outperform the stock and GP IC's.

They will take longer to heat up and keep the inlet temps more stable/constant for much longer.

[batou]

Quote: Originally Posted by GT4 Baz (original)

Slightly off topic but back to the inetrcoolers.....

DOn't forget the larger IC's act as a heatsink so while you might not see a power gain over the GP one with a GRS over a few dyno runs, it does have a giher specific heat capacity. So over a period of high rev activity (on the track or a back road thrash), the larger GRS and GTT IC's will outperform the stock and GP IC's.

They will take longer to heat up and keep the inlet temps more stable/constant for much longer.

That is a very interesting point... I think I've pretty much settled on my next change and was looking at a GP/GRS intercooler

[MINIdriver85]

Quote: Originally Posted by roland2003 (original)

Yes Stage 3 uses Ultrik valves. Stage 4 Uses Shrick .
Ultrik are cheaper and smaller and what many 'big valve' heads use. The Shrick Exhaust valve we use is 2.8mm larger in diameter than stock.(that is BIG) .
But the GTT CNC milled seat and throat ,...thats even bigger!
5mm bigger in diameter than stock to be exact .
If you calculate the increase in cross sectional area of the Exhaust valve seat internal diameter or the throat..... thats an increase over stock of 63%.

Roland, just to know, which valves do you reckon better, shrick or supertech? i've always thought the supertech valves were the best available...am i mistaken?

[roland2003]

Big Show, no youve got it wrong.
The head,cam,extra 3% on the pulleys & GTT fuelling changes added 41bhp to a car already fitted with a modded head (ie a GP head ,which has the same big port head as the JCW). What we're saying is, had the car prior to these mods been using a stock MCS head ,it is fair to assume the increase would be greater ...not the final figure you understand ..the delta.
As a made up example..... if a car has a stage 2 head and is then changed to stage 4 and gains 10bhp. Thats 10bhp 'over stage2' but over a stock head could gain say 40bhp......
-I thought I explained it well the first time.

[BigShow300]

Thanks for the reply and for clearing that up... So that means I should get a minimum of 271 bhp with your mods and even more possibly becuase I've only got a stock head.

[Ant FR]

overall, where is the biggest change in head work of all the stages.

Ie, comparing fromt he following.

1) Standard head jump to Stage 1
2) Stage 1 jump to Stage 2
3) Stage 2 jump to stage 3
3) Stage 3 jump to stage 4

say is each stage worth for arguments sake say 10bhp. Or is th biggest change as i am thinking going from the standard head to stage 1. If that makes sense.

Also is a stage 1 head say a GTT one or the Wilcox one, a better option than a JCW head?

[alski]

Quote: Originally Posted by Ant FR (original)

overall, where is the biggest change in head work of all the stages.

Ie, comparing fromt he following.

1) Standard head jump to Stage 1
2) Stage 1 jump to Stage 2
3) Stage 2 jump to stage 3
3) Stage 3 jump to stage 4

say is each stage worth for arguments sake say 10bhp. Or is th biggest change as i am thinking going from the standard head to stage 1. If that makes sense.

Also is a stage 1 head say a GTT one or the Wilcox one, a better option than a JCW head?

as above assuming 17% pully, uprated intercooler/CAI and manifold just to knock out some variables

[roland2003]

Hi Guys, difficult to quantify which level offers most gain on particular setup but the 'big steps' in flow capability are Stage 2 and 4......The fact these are what we use /have used on our own car is no coincidence. -Flow capability is everything .

[GTT 280]

you did.

[roland2003]

Ah you found it then

[GTT 280]

Quote: Originally Posted by BRMCooper (original)

it seems like theres only one way to find out for sure

I'm ready for a Stage 4 now, but need to find a good home for my Stage 2 head first

Cheers,
K.

[CC07ERS]

I wish i had a supercharged S

[GTT 280]

I've just been re-reading this thread and i must admit, i'm very excited at getting the new stage 4 head. Other than power alone, i'm very interested to what exhaust tone change it creates, i think i have already loosened a baffle in my milltek exhaust from my Stage 2 head

Also going for the new Top Mounts and a full ProFlex bush upgrade (and an AFPR, Rear Strut Brace, and new Rear Spiroslot Rotors and Red? Pads) ha ha

...but i don't mind eating baked beans for every meal !!

I'm currently organising a RR session before and after the Stage 4 head so hope to get some saucy graphs posted up here soon. I beleive this will be the trickest SCahrger car from GTT to date (now that Roland's dismantled his charger into a turbo!)

I'll have to race you 0-30 (just before your Turbo spools!!!)

See you in early March fellow!

Off to Oulton Park on Wednesday (30th Jan) with the bullet cam and a 30:1 OB mixture

Bye for now.
K.

[danpd13]

Exciting Stuff,


Just put the deposit down on my Stage 4 head, can't wait!!!

[Jaw_F430]

Quote: Originally Posted by danpd13 (original)

Exciting Stuff,


Just put the deposit down on my Stage 4 head, can't wait!!!

What other mods do you have on your car at the moment? Will you dyno it before and after?


James

[danpd13]

Quote: Originally Posted by Jaw_F430 (original)

What other mods do you have on your car at the moment? Will you dyno it before and after?


James

basically its a standard mcs works at the mo, plan is to have gtt 220 conversion but with stage 4 head, cams, pistons, and Variable fuel pump, as well as clutch diff and flywheel, then go for the 280qs conversion in the future, i'm doing it this way so that i waste as little money as possible on parts that are not used in the 280 kit, rather than going all the way down the supercharger route then having to remove stuff and sell it etc..... not too fussed about RR figures, if Roland says it will do it thats good enough for me

[alski]

thats a bit of an understatement........