Another couple of questions from a Newbie?

[Chesney84]

Hi chaps a couple of questions if any of you could help, some may be stupid but a complete newbie and can’t find out what’s what:

1) Standard position for battery- mine is fitted to the passenger side in the scuttle but seen photos of them mounted on the RHS (in front of the driver)?
2) My car has no jack or wheel wrench- would this be mounted in a bag in the boot or in the scuttle area opposite the battery (depending on which side the battery is)?
3) My car has aftermarket boost hoses, but seeems to be missing a port that many seem to have- the top boost hose from intercooler to lobster, has provision for a dump valve, but next to the lobster many have another outlet leading to the bulkhead, but mine doesn’t and I can’t see what it would go to or be for!

Sorry if some of these seem obvious but I’d really appreciate the help!

Cheers, Andy

[Ian S]

1) passenger side is correct. To put more weight on the left as the UK driver sits on the right.
2) bag in the boot.
3) It was for a pipe to a solenoid valve so the anti percolation fan to blow air into the boost hose and cool the intercooler and turbo.

[Chesney84]

Thanks Ian, my anti percolation fan system has been removed so that explains why I can’t see where it would go! Cheers!

[Chesney84]

Hi guys

Quick question, what sort of power is the standard cast exhaust manifold capable of before it starts holding back the airflow? Seen a lot of bad press about numerous brands of tubular exhaust manifolds cracking, so with this in mind was considering porting and polishing a standard cast manifold and then getting it ceramic coated. Any advise would be great, just bought a block and embarking on a full build from scratch, with water-methanol injection and Holset Turbo (aiming for the 250bhp mark)!

Any other advise or potential pit-falls (apart from cost) would be great as this is my first 5 and have very little experience with Tuning them

Cheers Andy

[markg]

Standard manifold will be fine. In fact out of all the high power C1J's I dont think any were running tubular, hence there are simply no figures either way to prove or disprove any benefits from changing. That being said I have a tubular to fit on mine but more as a experiment than anything. If I miss the burble will probably fit an original back on.

[Chesney84]

Thanks mate, I do like the burble you get with the 5. I’ve quite a bit of experience with Impreza’s and there was always the same dilemma as to whether or not you went to equal length headers but lost the boxer sound!

[Ian S]

One of the most powerful non NOS 5GTTs was a member named Bu$hy, 247BHP, 32DIS carb, standard manifold. About 25PSI, from a 'Tomcat' spec turbo, nicely ported head from CTM in Dagenham, matched to the manifold. Standard valves I think. Did an 11.9 second pass at the pod.

Polishing is not better, it's worse, the rough finish causes the touching air to eddy and the passing air then more easily rolls over it, slightly less drag, slightly higher port velocity. See: Boundary Layer Theory.

The original manifold is cack though, we passed air from the compressor into each inlet and felt the outlet, it flows better from the water pump end, but stalls from the gearbox end. However with higher boost there could be 60psi in there, so scavenging, flow etc, less of an issue. Someone I know had a very nice 4 into 1 made by Simpsons Exhausts (no relation to me that I know of), about £1000 or something, IIRC, he reported that the difference seemed with to be off boost and coming onto boost, but not much.

I can say from my own experience that a nice 2 1/2 pipe from the turbo makes a LOT of different compared to the OE rubbish. Going into a free flowing exhaust, such as a 2 1/2 incher. The Collins (Blue Flame) 2 1/4 was also very good and made a particularly nice sound, like a trombone, then a trumpet.

From: https://www.rtoc.org/boards/showthrea...GTT-April-2011

POWER/TUNING

The Phase 2 5 GT Turbo left the factory with 120 BHP which does not seem very high now compared to many modern cars, however as the car is very light at 830kg the power to weight ratio is quite high and a moderate increase in power can give impressive results. Many people strive to reach 200 BHP and to achieve this, the RTOC recommend the following modifications:

• Correctly re-Jetted standard venturi’d carburettor set for 20 to 25psi of boost.
• Free flowing exhaust with larger bore from the turbo back all the way through to the tail pipe. Not one with a restrictor or narrow baffle.
• T25 or T28 Turbo set to 20 to 25 psi; a favourite is the ‘Tomcat Spec’ not the actual Tomcat turbo. The larger the turbo the more power and the more lag.
• Stronger actuator, preferably the T3 type with a -12 spring.
• Actuator piping changed to the ‘Cup Racing Series’ Modification.
• Delete the rest of the boost compensation mechanism as it has no effect once a decent low back pressure exhaust is fitted.
• Boost gauge to read manifold boost pressure or you’ve no clue what boost you have as the OE dash gauge reads the pressure before the carb.
• Larger than OE intercooler with alloy welded on end tanks and generally front mounted.
• Different camshaft profile, a favourite is the 285 @ 110°.
• Stronger clutch, normally the Valeo Volvo 480T, with 'soft pedal' conversion.
• Firmer engine mounts to check the extra engine movement.
• Normally silicone boost hoses and new OE or silicone water hoses as old OE items tend to split. For reliability this applies even if you’re keeping standard power.
• Oil pressure gauge to show you the reading at the inlet to the turbo.
• Adjustable bracket for top dead centre sensor to allow timing to be backed off a few degrees.
• Bottom pulley from a Campus engine; it’s smaller diameter turns the alternator / water pump slower and doesn’t throw off the belt on sudden lowering of high engine rpm.
• For long term turbo reliability, not noise, a double piston dump valve, possibly re-circulating for no noise at all. Double piston as they keep the inlet pressure up when off boost giving more responsive get up and go.
• A crankcase breather oil catch tank will probably be required.
• Taking the inlet air from a cold place near the font of the engine bay through a decent flowing filter, possibly trumpeted.
• For reliability, new valve springs, possibly longer, harder and in lowered seats to match the taller cam. Possibly new collets. Possibly rocker faces over the valve stems reground to remove the edges worn by the standard cam. No need for valve seats, throats, ports, matching manifold at this power level, it will yield little power for the expense.
• NB: Modify at your own risk! This is not a detailed list, just basic guide. It's not the RTOCs fault if your engine fails after only a few minutes because you didn't understand what to do and didn't ask the right people the right questions!

[Chesney84]

That’s great, thanks for the reply and advice Ian. A colleague at work, an old boy, has a long history in engine building (from BMW F1 Turbo era to currently building 3500bhp drag engines) and has said he will build it with me and show me some of his tricks. He mentioned as well about not polishing the head for the very same reason- just to do the porting. Oh and got my ticket today for the Retro Show thanks, but engine won’t be ready by then!

[Matt Cole]

Make sure you do a project thread Chesney, especially noting them 'tricks'😉

[Chesney84]

Will do, have begun a photo diary of the strip, block was collected Saturday AM, stripped Monday evening and is going to the acid dippers on Thursday then will be followed by hot wash!

[Matty]

Personally I always use equal length where possible to ensure even scanvenging between cylinders and uniform mixture on all cylinders. You will find that log style manifolds don't necessarily restrict the peak power figures, but you can generally run less boost to get the same amount of power. Your turbo should spool quicker with an equal length, due to the pipes being smaller which keeps the gas speed up...log style tend to be larger bore than necessary to improve their efficiency, but this tends to kill the gas speed and creates more lag. A larger downpipe will also help with spool up and peak power.

Definitely interested to see the 'tricks', ive tried quite a few.

i was tempted to fit some under crown jets to mine, but got wanted to get it finished for this summer.