Jump to content

Highly Tuned GT6 Engine/Camshaft Question


FlyinPhil

Recommended Posts

Hi,

This is my first post in a forum ever, so please bear with me.   I a Mk3 GT6 with a very higly tuned engine which was originally built (not by me!) to do track days and the occasional hill climbs etc.  Everything in the engine is brand new and has just been run in.  Below is the list of everything I know which has been done :-

Blueprinted engine
New +0.080mm forged pistons
New/Old Stock Un-commissioned Engine Block, Lined Bored and Cam Journals fitted
New Crank, Balanced
New lightened Alloy flywheel
New Cylinder Head, Ported & Gas Flowed, inc Stainless Steel Valves & Phosphor Bronze Bushes
Unknown high lift race cam
Timing Gear, Rocker Shaft & Duplex Timing Chain Conversion
TR5 Distributor
Reconditioned Lucas P.I. System - All injection parts are new. The inlets are the early 150bhp ones which have been lined bored to accept the later Mk2 spindles.
Custom Throttle Linkage by Prestige Injection
Prestige Injection Bosch Fuel Pump Conversion
K&N air filter.
Balanced AP Lockheed Fast Road Clutch and Cover.
6-3-1 GT Extractor Manifold into Bell Twin Outlet Stainless Backbox
Alloy Front and Rear Engine Plates
Alloy Thermostat Housing
Alloy Water pump

I have nearly completed turning back into a fast road/ track day car however I want to fit a different camshaft as Aldon Automotive can't tune it properly for road use with the current cam as it has such extreme valve overlap.  They have tuned it very well at full throttle and idle but can't get it right at part throttle and I'm concerned about bore wash.  

I wanted to know what you guys would recommend to be the best camshaft to go for considering the type of engine it has.  I have been swinging towards the Kent TH5 Sports 'R' - is this a good choice or should I fit the standard TR5 150bhp cam ?

I am kinda new to engine tuning and now a bit lost.  Please help, any advice will be greatly appreciated!

Link to comment
Share on other sites

FlyinPhil wrote:


Blueprinted engine
New +0.080mm forged pistons
New/Old Stock Un-commissioned Engine Block, Lined Bored and Cam Journals fitted
New Crank, Balanced
New lightened Alloy flywheel
New Cylinder Head, Ported & Gas Flowed, inc Stainless Steel Valves & Phosphor Bronze Bushes
Unknown high lift race cam
Timing Gear, Rocker Shaft & Duplex Timing Chain Conversion
TR5 Distributor
Reconditioned Lucas P.I. System - All injection parts are new. The inlets are the early 150bhp ones which have been lined bored to accept the later Mk2 spindles.
Custom Throttle Linkage by Prestige Injection
Prestige Injection Bosch Fuel Pump Conversion
K&N air filter.
Balanced AP Lockheed Fast Road Clutch and Cover.
6-3-1 GT Extractor Manifold into Bell Twin Outlet Stainless Backbox
Alloy Front and Rear Engine Plates
Alloy Thermostat Housing
Alloy Water pump


Wow nice! I think couple of items are possibly over-board for a road car, (alloy water pump and ali flywheel). I have a GT (Mike the Pipe) 2.5 in my Spit with various of your other goodies and I find the standard GT6 flywheel light enough. I only have the Saloon 132bhp cam and I find that adequate. Either cam will do if it's a 2.6(?) Give Chris Witor a bell for more interactive advice (he'll sell you the cam as well!).

The 150bhp TR5 will do fine and the TH5 will give a bit more power, but still a wide torque band.

Andy Thompson may be able to give some personal experience/advice.

ps in the Spit I have a 3.63 and 14'' wheels (195/65 x 14)

Link to comment
Share on other sites

Hi Guys,

Thanks for the replies and advice, in answer to your questions I have the standard GT6 2000cc block overbored (which i believe makes it a 2.3?) and a modified metering unit to suit.  

Its running a TR6 gearbox with J-type overdrive mated to a 3.27 diff, and it has 185/55/14's.

Some of the items do seem a bit overkill as the guy I got it off spent stupid money on it, but as they say overkill is a good kill !  Any how it sounds amazing and is very responsive, almost motorcycle like, so i'm not complaining.

Link to comment
Share on other sites

Watch that diff; it's a bit weak. 3.63 is the strongest and a 3.89 would have been the standard for a UK O/D GT6. The box will be strong enough, but the diff?

ps I broke my 3.27 but then the 2.5 torque is more than a 2 litre, not sure about yours?

Link to comment
Share on other sites

Yeah, I know its not the best however that and the overdrive have been uprated to take the extra power/torque.  The OD & Diff have both been uprated so I'll just have to see how it goes.  In its current guise it is more top end than torque so I might have a few issues when I swap the cam, but fingers crossed it will take it ok.

Link to comment
Share on other sites

Watch your compression ratio, if the head has been skimmed to suit a wild cam it may be a bit high for a more standard cam?

If Aldon can't tune it that's surely because they don't know how to calibrate a PI metering unit. Maybe you need to talk to KMI (is that what there called?) to get it calibrated?

Link to comment
Share on other sites

Hi Phil, for a 2 litre PI I was recommended to go for a 37 67 71 33 camshaft, with the lift about .410 for fast road and occasional track use, though I am not sure if this is any less wild than your existing camshaft.

As CharlieB suggests, Aldon may not be fully versed in the (now) old Lucas mechanical injection system. I know KMI (Keith Mills Injection) supply metering units for the 2 litre PI, but I am not sure if they actually know how to alter the settings correctly for a specific setup.

Link to comment
Share on other sites

I am a little concerned about the compression ratio, but unfortunately there is no way I can work it out as I don't have enough information on it.  Aldon did say they arn't very experienced in the PI system however they had done a couple before, but to be honest I just don't know who to take it too to get it setup, and they are quite local which is handy too.

Surely the metering unit can only be setup on a rolling road to the specific engine its on, as its very improbable that every engine is the same but this PI seems to rely on witchcraft as far as I can tell.  As it stands the fueling is fine on full throttle and idle, its just the bit inbetween which is proving to be an issue.  Aldon advised I had three ways to deal with it, 1 change the cam, 2 stick triple webers on it or 3 go EFi.

I have spoken to jigsaw and told them the specs and they have advised me to go for a TH5 or 6, which is probably where I end up and hope that the compression will allow for it, unless there is a another way to work it out.

Link to comment
Share on other sites

The metering units usually come pre-set for a specification. Have a chat with Malcolm at Prestige Development.

I think the philosophy is 'have a metering unit that always runs slightly rich then you wont burn out the valves'. :)

Link to comment
Share on other sites

At the risk of inviting negative comments, you could try contacting Gareth Thomas for help with the metering unit.
Yes I know his forum manners may not be to everyones taste, but he does know his stuff about PI systems, especially for the 2 litre and may well travel out to you.

Link to comment
Share on other sites

FlyinPhil wrote:
I am a little concerned about the compression ratio, but unfortunately there is no way I can work it out as I don't have enough information on it.

Can't you ask the previous owner?
If not I gues its head off & measure.

Link to comment
Share on other sites

CharlieB wrote:

Can't you ask the previous owner?
If not I gues its head off & measure.


Unfortunately this was one of his projects he was doing at the time and just gave big wods of cash to other people to build it.  He had no real input or interest in the real techie details whatsoever and has since lost contact with the builder as it was quite a while ago.  However its a good job I like a challenge this is proving to be one, hence me turning to you'z guy'z.
However in the end it may well be a head off and measure as you say, or I could just thrash the pants of the thing everywhere which is also very tempting!

Link to comment
Share on other sites

Lovely spec car  8). I share the concerns raised that Aldon may have been well intentioned, but recommending fitting triple webers?!? I wouldn't be surprised if they are indeed 'rusty' on the finer points of PI.
KMI or other Lucas petrol injection specialists are a better bet. GT is very knowledgable about this sort of thing, though as he lives abroad, you have to be realistic of what he can achieve.
Before you splash any cash, do loads of research, then do even more! :)
  

Link to comment
Share on other sites

Richard.  If you hadn't banned Gareth he could chuck in his two cents worth and it certainly wouldn't be to use a TH5 or TH6 cam.

Phil, I am sure if you dropped GT an email ( admin@jagclub.ru ) he could offer sound advice for what sounds like an engine with excellent potential.  Stick with the injection it will howl.....  :P

Link to comment
Share on other sites

Andy - thanks for that, I think I'll send him a message and yeah it does howl! :o  
I really want to stick with the PI, as all of the modifications the car has had are from Triumphs, apart from the rear discs which are from an MGF.  I'm in the process of getting some video of it which i'll stick on youtube and post the links on here.  Thanks for the info everyone - it nice to know there are so many people out there willing to help!

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...