Race Engine Forum UK

Hello,
First post so... I would like to congratulate Guy on an extremely well run and well behaved forum. The amount of information that can be ascertained from this forum is unbelievable. I am working my way through all of the posts to bring myself up to speed on language and engine concepts. I have spent many a night starting to read and then finding it 2:00am as if no time had passed. Guy, you have also left me with several headaches pondering engine building concepts. This is like taking a university masters course in engine build. Well done!

On with my question. I have had the 2.0 TC 8V for almost 22 years and think it is time for a recharge. I like the reliability of the L-jet system and would like to keep it installed, but would like more power (who doesnt). From Guys writings, power is in the head, so I would assume that porting the head and manifolds is a given. After that, what can be done to produce HP without adversely effecting the computer. A short list of parts and procedures that would be necessary would be appreciated. I think if I had a carberated engine, I would know what to do, but this Bosch L-jet just throws me for a loop. I know this is a race site but most of these principles correlate to a wild street ride also. What realistically can I expect from this build in terms of power?

Guy, would you recommend your triple valve springs and adjustable cam wheels for all TCs? I have broken a valve spring before, causing a few dings in the piston top.

Great work, thanks
Pope

Hi, thank you for your kind remarks!

The most I have had is about 135bhp on flowed head and std cams, slightly higher CR. Very torquey, very driveable, way quicker than standard, I should know, I drove it to prove out the fuelling with gas analyser on board. To be honest I just did not think at that time (90's) that the L Jet system flap meter would cope with the aggressive pressure waves from a cam change so I did not take a chance on it. I think we raised the fuel injection pressure about 4psi and that was that. The car (US spec 2L 8V Spider) belonged to a UK client namedTony Dark and it was featured in my manual; the car is now in Italy, the new owner rang me some weeks ago!

I have to say there as many opinions (some based on exp and fact, some not) on tuning that FI system as the day_is_long! But fundamentally I will say it would be quite easy to upset the very delicate calibration of the L Jetronic airflow metered fuel supply. Even the seminal book on Bosch Fuel Injection by Charles Probst (Bentley Publishing) says so - and I read that long after we did Tony's motor! In my view to take a chance on modifying the unit or running as-is, well - that risks damaging the whole engine. And I know plenty of cases of that.

My advice is do no more than I did! As for springs - if the cams are standard use new OE springs, they're fine. No need to use adjustable camwheels unless the cams are changed or much (over 10 thou") milled off head and block.

Thanks again for studying the site, I do wish more people would read and use the search before posting!

GC

Hi,
Thanks for the reply. How did you get the 4psi boost in fuel pressure? Did you replace the fuel pressure regulator on the fuel rail with an adjustable regulator? How do you feel about the rising rate fuel regulators on the market? Do the stock injectors supply enough fuel or would it be OK to replace then with injectors that are maybe 25% larger?

Thank You
Pope

Leave the injectors alone, use a Webcon rising rate regulator. Hook up fuel pressure gauge (0-60 psi) into the injection rail, read off the idle pressure and note it down. Fit new reg and calibrate at same rpm to that setting plus the extra psi.

Sorry for brevity, v busy today..

G