What Power Would You Reckon

[johnboy]

Hi guys, my A series is running a low mileage 2.0s motor with a stainless sports exhaust, twin choke weber down draft carb with a free flow air filter and electronic ignition, what sort of power do you think it could be making with this set up, it does pull really well right through to the red line, i only ask as i was thinking about a gte engine swap (you may remember my earlier post about fitting a gte engine and box) but after using it for a couple of weeks now i might stick with the current set up and just go for a five speed box conversion, not trying to be anal or anything but was wondering if a 2.0cih gte swap would give any gains or not? cheers John

[Rick-Manta]

No point in swapping. Were you planning on swapping the fuel injection system too? The GTE lump is basically the same as what you have but with the electronic management and ignition. The 2.0S is 100bhp and the 2.0E is 110bhp as new and standard for a comparison.

[johnboy]

To be honest retropower has an engine and box for sale on e-bay that i was thinking of fitting complete with the injection system etc but i read somewhere on here that with the mods i have and some porting and polishing then around 120bhp was achievable??

[opel2000]

I had 2.0S running:-

Weber 32/36 DGV.

K&N with the breather hose from rocker going into rear of air filter and branching off to smal port in inlet.

PMC exhaust system, absolute wonderful system this was. 2" straight through.

Electronic ignition.

Viscous Coupled fan.

Head was gas flowed with material removal on the exhaust port area, and slight waisting of the exhaust valve stems.

Carb had all the casting flashing removed and some material removed from the (can't remenber what they are called) the bits that that cross over the Venturi.

Inlet manifold had as much smoothing as possible (not easy to get in there)

Carb was supplied jetted for 2.0, but could not get engine to idle smoothly, after weeks of p1ssing about and my speeding ban lifted, i took car to John Wilcox Competition engines at Hinckley to get it on their rollers and for them to sort it out.

Apparently the increased flow through the engine was causing problems, they "Eventually" fitted different idle jet/s and the peaky dyno graph was now a steady smooth line.

Engine was producing 101 BHP @the wheels.

This dismayed me somewhat as the engine was supposed to be 100 BHP from the factory, until I realised that the faactory figures were Flywheel figures and was told that from engine to wheels you can lose 20 - 30 BHP through the drivetrain.

The man in charge (John Wilcox) had years of tuning Manta engines in the past and said if I had turned up with twin Webers he could have looked up all the past figures for setting these up.

INTERESTINGLY ENOUGH......... He went on to say that he particularly liked the way I was feeding the crankase fumes into the carb through the rear of the air filter as engines do runn better this way, and slightly richer too. NOW that is from the voice of experience, and from someone who's day job is getting the most performance out of engines, so a damn good dig at the fools that thinking adding a little breather filter thing is a good idea........ It isn't.

Car was a Silver W reg 'B' series hatch. And wouldn't pull the skin off of custard when I got it, and never in a grillion years would I p1ss about again with a crappy varijet, engine was actually cobbled together out of bits i had lying around apart from carb and exhaust which i brough new.

Car drove spot on, and was great fun, at the time I used to drive over to Nottingham and Lincoln a lot and used to get fools trying to pass me as soon as traffic cleared, used to have great fun getting the revs up and throttle position just short of the Secondary on the carb ready to open, and as the car behind used to start closing up, i would open the throttle and see their jaw drop in the rear view mirror as i accelerated away from them.

I guess next step for me would have been slightly different cam to add a few more horses followed by bigger valves and that would have been it really to maintain smoothish idle and driveability.

Absolutely loved that car, and that was the last 2.0Cih I had, and if I was going to have another I would not use the injection but go this route again.

[johnboy]

Interesting reading that, opel2000, good food for thought, think i will stick with the set up i have, might experiment a bit with some porting and polishing etc, cheers Guys

[opel2000]

Wish I could remember the site I picked up the exhaust port info from, as they had done extensive mods to find out what worked and what didn't.

To me the argument that flowing the exhaust area is a waste of time due to the gases being pushed out under pressure is 8ollucs, simply put if you can reduce the amount of pressure required to push the gases out, then engine will be more efficient.

[MANTAMAN]

Currently there is a Cavalier Coupe GLS listed on flea-bay and they detail engine mods they estimate to give 130 - 140 bhp -

link to Cav Coupe

Once boughts some parts off a Manta nut who was having a clear out, he claimed that if you did a proper job on the valves,ports and inlet manifold,decent cam, put on a good exhaust and replaced the original carb with the down draught intended for a three litre Capri (sorry swearing on the Manta site!) then well over 150bhp could be had, not sure what that would do for the fuel consumption but cant have it both ways.

Edited March 15, 2011 by MANTAMAN

[lamchop77]

Wish I could remember the site I picked up the exhaust port info from, as they had done extensive mods to find out what worked and what didn't.

To me the argument that flowing the exhaust area is a waste of time due to the gases being pushed out under pressure is 8ollucs, simply put if you can reduce the amount of pressure required to push the gases out, then engine will be more efficient.

Try Rallybobs articles on opelgt forum. He has done alot of race prep on 1.9, 2.0, 2.2 and 2.4 engines. All the work has been done using a flowbench.

Flowing the exhaust area is not really needed as a rule on the CIH as the port flows at something like 75% of the inlet with the std valve. This ratio only needs to be something like 60% so you can increase the inlet flow by quite a margin before the exhaust really needs to be touched. a quick clean up will do no harm though.

Porting the inlet and fitting 45 mm valves has a big impact on the flow through the head. got an article by Dave Walker who did all this and measured after each mod. I'll try and get the info and post it here.

HTH

Chris