Engine development

[foggyjames]

Hi guys,

Here's the situation...I want to alter the power delivery curve on my 360 so that it retains the current mid-band torque, but 'kicks' like a modern 16 valve unit at high RPM (far from beyond a suitibly tuned 8v motor). I'm not looking to build a fire-breathing monster, but an increase of around 20-30bhp, and more to the point a change in where it is delivered is what I'm after. I've got up to £150 to spend on achieving this, preferably a lot less, given that 'Plan A' was going to cost around £75 incl tuning on the rollers!

Unanimous opinion is that the cam is fundamentally to blame. The initial plan was to swap in an 'A' cam (740 turbo or 360 GLT), which was modelled using CAD as giving the desired effect (with tuning to correct the fuelling). However, the GLT only delivers an extra 10bhp more in an otherwise identical engine, so either the cam data was wrong (possible) or the injection system in the GLT is 'detuned'. I've got nervous about this now, as I could spend a fair bit of money for little result.

What I need is a positive answer regarding what an altered cam will do. The CAD package (Dyno2003) is a totally genius bit of kit, and told me exactly what I wanted to know, but it assumes I've put the right data in...and no-one's that sure of the accuracy of the cam data. What I need is an engine development bod.

I think my request is beyond the scope of the forums (even the most technical), but the question is who do I turn to? Custom cam manufacturers? Engine development engineers (like Noble)? This is all getting expensive sounding - I only want a fairly minor change (albeit to a complex part of the car)!

I've heard a lot of opinions on this, and thanks to you all (not that very many of these people will be reading this!), but I know better than to believe any one person (unless they are famously expert...a rarity when it comes to cars!).

Any thoughts?

cheers

James

[Ross9]

I would be very surprised if you can achieve 20-30 BHP with £150 on a non-turbo car.

For a start, in order to get this gain, you have to increase torque at higher rpm, as torque multiplied by rpm, plus other constants, is BHP (in essence just a number, torque is a real force) and to create more torque you basically have to cram more air into the cylinders, I cant see a change of cam getting enough extra air into the engine and out again to create a further 20-30 BHP. Not from a single cam, no matter how extensively it is designed, and you dont have a very large budget.

To gain 37 BHP over standard on my own car I had to fit a bigger turbo, FSE fuel valve, atmospheric DV (no recirc on the new turbo) adjust the boost to 13psi constant as opposed 7 rising to 11. This cost a LOT more than £150 lol, and it was on a turbo car, which is generally easier to get more power from by upping the boost a bit. This 37 BHP was accompanied by a hike of 46 lb/ft, or 62 Newton metres, a cam just wont shove that much more air in, it could shift what torque you do have further up the rev range though, resulting in that kick you ask for, but would sacrafice your mid range in the process, and again it would have to be a very good cam to get 20-30 BHP in my opinion)

I cant see a cam getting you 20-30 BHP, on most naturally aspirated cars I think gains of 10-15 BHP are seen as very good from fast road cams, and that's using adjustable pulleys to set the cam timing.

If you can get 10 BHP for £75 thats pretty good in my opinion, and I would be happy at that.

I dont know anything about the engine you refer to, perhaps everythign I've said doent apply, but all engines follow the basic principles so hopefully it's relative.

Hope this helps

Ross

[Cypher007]

i toyed with the idea of supping up my 360glt some years ago. in my opinion the cheapest way to do it is to get an old 740 16v 2.3 unit and put that in. its a tight fit but has been done. i heard one guy who was running one of these units at 163bhp, after tunning. so you could probably go over a breakers and get a secondhand engine within your budget. then spend some time sorting out how to mate it upto the existing equipment :).

p.s. ive just had another idea, you might be able to just fit the 16v head on top of your 2ltre unit. if you then loose the back box from the exhaust system, fit a bigger throttle body, bigger injectors, and a high flow panel filter. you might achieve the 20-30bhp your looking for. some of these mods were a favorit with vw golf gti owners, they use the same jetronic system.

[foggyjames]

Hi Guys,

Firstly, I'm well aware of how to 'do it properly' as it were....long term plan is to fit a 2.3 turbo 740 lump, but I can't afford the insurance at present...

Dyno2003 suggested I could get circa 22bhp extra and about 750 rpm higher....but this assumes the cam data is correct. It got my stock power right from raw figures, so I believe it (provided all data is right).

Under normal conditions, I agree that there's no way you could do this on the budget, but this engine feels so extremely 'detuned' that I'm sure it wouldn't take much. What I'm trying to do is restore a more 'natural' power curve to it, rather than one that's artificially squashed (for fuel economy & drivability?) due (almost certainly) to a weedy cam and conservative fuelling. I'm being realistic about what is possible, and I'm just quoting 20-30bhp as a ball-park figure, but given that its power is already falling off at 3krpm, just opening up the top end to a natural peak (surely simply a matter of camming?) would be enough for me. I'd assume that the *height* of that peak depends on things like gas-flow (given that my engine flows quite well already in comparison to most) and a big-bore carb setup (DCOE45s etc), while *position* of the power peak is cam related?

cheers

James

ps: forgot to say, see attached dyno2003 graph, thanks to Mike (RavenNexus) for that one!