big power engines

[garym]

what valve train and cams are the big power engines running, what can be expected from std setup, can anyone advise on racing valves or will std do? also springs and cams?

[Gringo]

Define "bigpower" please.

[garym]

big power engines

450/500 bhp plus

[Gringo]

Stock head, springs, lifters/retainers, valves, 7A cams optional.

Switching to a ported head, harder springs, lighter lifter/retainers won`t give you more HP pr say, but it will increase RPM range and driveablity.

Larger valves and more agressive cams will however increase HP substantially.

Mech lifters is recommended beyond 8200rpm and with most top end cams ( often seen only with a profile for mech lifters).

A dry sump system is also highly recommended beyond 8200rpm due to failure prone stock oilpumps at this level.

[DJones]

Gary you will easily get that sort of power from standard valves. Never seen the benefit with bigger valves on turbo engines, especially multi valved engines.

7A exhaust cam is a good alternative to standard as it has more lift and not to compromising on overlap.

You can play around if you fit adjustable cam sprockets (chain sprockets not belt sprocket) but this is usually just to dial out surge.

After that its solid lifters for high revving engines etc..

[garym]

big power engines

thanks for info,i just feel something is not right with what i have, engine spec is as follows , audi sport billet crank and works dry sump system, h section rods ,dont know what pistons but they are not slipper pistons approx 9 to 1 compression ratio ,ported head with solid lifters std valves not sure about springs, no idea about cams as builder will not tell me ,engine giving 430bhp on super unleaded with octane booster, torque about 360 ft lbs ,engine seems harsh in its power and dont run on past 7500rpm, we have audi sport s1 inlet and exhaust manifolds on it with a garrett gtr 35 turbo,,even though the flywheel has been lightened it isnt sharp it seems to pick up smoothley but not quickly compared to other cars ive driven ,to be honest i was expecting more ,any ideas,almost forgot we are running motec ecu setup

[Error404]

should be making much more than 430 with that spec surely? Perhaps the "mystery" cams are the issue?
I'm no expert on these matter, far from it - but isn't a GT35 good for at least 500 - 550hp with appropriate supporting kit?

[Beetie]

Seen a few recently going back to solid lifters...

[speeding-g60]

my 35R made the tires spin on the dyno @ 550 whp on my 4cyl 20v....

[garym]

big power engines

im not looking for more than 450/500 bhp in fact 450 is more than enough for what i want ,what i am missing is the punch out of corners and the sharpness on and off throttle, i think the cams must be pretty mild and the builder is using boost to get the power and not worked on throttle responce and pic up, im wondering if anyone knows of some rally cams that will give the responce i want without going wild on boost ect

[Gringo]

Telling you what`s wrong with your setup based on info typed in on a forum is like asking a pig to sing the national anthem. Hard

I cleary understand what you are looking for, but the solution isn`t on here. It`s at the dyno. Having more information about your cams and the setup of them would certaintly help. The fact that your builder isn`t willing to give you information about something you bought from him strikes me as odd.

I would assume your tune/map sucks. With the parts you have mentioned you should see way more power from that engine. Find another tuner.

Mine puts down 503whp with 95oct unleaded RON with a GT35/40R and I don`t have more than half your list of parts.

[lind4hl]

is it for some type of racing car?

then i would change the exhaust valves to inconel, instead of the natrium-filled OEM ones

ESPECIALLY! if you´re using ALS/Launch control

[s2_bo]

Are you based in england? Maybe give MRC a call and arrange a date to take the car to them. They can check it over, work out whats going on or whats going wrong and remap it if thats all whats required.

[LHD_Kid]

Are you based in england? Maybe give MRC a call and arrange a date to take the car to them. They can check it over, work out whats going on or whats going wrong and remap it if thats all whats required.

Can MRC map MOTEC?

Does sound like it needs a decent mapping session....

Good luck!

[Jonnybravo]

Gary you will easily get that sort of power from standard valves. Never seen the benefit with bigger valves on turbo engines, especially multi valved engines.

7A exhaust cam is a good alternative to standard as it has more lift and not to compromising on overlap.

You can play around if you fit adjustable cam sprockets (chain sprockets not belt sprocket) but this is usually just to dial out surge.

After that its solid lifters for high revving engines etc..

A C20LET/Z20LET Vauxhall engine has a restriction due to the valves so its not uncommon, material type is the issue and the exhaust valves we use now are Nimonic 80 specially manufactured.

Cams, suitable headwork and larger valves all seem to play a big part in eliminating surge from big turbos even when the turbo spec is about as right as you can get it imo.

Getting most engines to make massive numbers isn't all that difficult, getting it to make it in the right place is and thats where it would seem the above is required but most (understandably) are happy to put up with a few issues as your talking a lot of money / development to improve the engine to that stage of tune.