Am i seeing the benefit itb's???

[Mudslinger]

looking back through mine and other car results from sundays rr day ive been able to get a bit of comparrison of how much benefit im getting from have the throttle boddies and the ex manifold.

here goes , im going to use glens as my example but forget the nos for a moment .

basically a standard built engine ,and cam using carb running a t28 @25psi made 190 or there abouts .

Mine although rebuilt the costly route is really basically the same apart from the 285 cam slight porting and a bit lower comp but running a t25 @25psi although spiked to 30 it made peak power with 25psi 270

80hp diff using a smaller turbo at the same boost ??

thoughts?

[5teve L]

Sounds good to me. I know it was expensive but who else can claim that power without NOS?

Wish i still had mine

[Scoff]

Your seeing a good gain because your engine breaths better for a bunch of reasons, not just improved throttle area. I know I've piped up about this before but I think you'd make as much peak power with a single throttle. maybe you are seeing some better responce at part throttles because of your ITB's ? I don't know. I don't understand them much, I only understand stuff that makes me go faster on the strip so my opinion is a bit one sided

Glenn's car minus the gas is a good example of what is possible with a standard cam. It reflects in the trap speeds that people regularly see with that kind of tune (108mph there about). Glenn could have pushed that upto 240hp with a good camshaft and good headwork, still with a carburettor. It will have taken some carefull jetting. That would be a 112/113mph trap speed. Making more power than that with a carburettor is hard work. I don't know how much easier it gets with a big throttle or ITB's because I havn't tried though I think you've proven that there is a lot to be gained, just keep in mind that some of that efficiency will have come from your camshaft and cylinder head too.

[Ashy]

I think you would see further gains with a bigger turbo, you've clearly removed the restiction on the inlet but throttled it somewhat on the exhaust side. 270hp is an impressive result tho Mud and shouldn't be played down

I'll go upload your video now, give me ten mins.

[michael tierney]

when using a single carb u will always get mixture robbing of the 2 inner cylinders as in 3-4 and 2-1 firing order.in other words just as the inner cylinder is coming to the end of its induction stroke,the outer cyl.inlet valve opens thus robbing the inner cyl. of its complete stroke.with independent throttles and manifolds your peak torque should have occured much sooner and been alot higher.the cams possible 10% will have been magnifed by the fact that u had no restrictions(venturi and 32mm throttle)what so ever! on the carb if u went to 27mm you'll find thats all that the cross sectional area of the throttle shaft plus screw heads actually leave.

[Mudslinger]

Your seeing a good gain because your engine breaths better for a bunch of reasons, not just improved throttle area. I know I've piped up about this before but I think you'd make as much peak power with a single throttle. maybe you are seeing some better responce at part throttles because of your ITB's ? I don't know. I don't understand them much, I only understand stuff that makes me go faster on the strip so my opinion is a bit one sided

Glenn's car minus the gas is a good example of what is possible with a standard cam. It reflects in the trap speeds that people regularly see with that kind of tune (108mph there about). Glenn could have pushed that upto 240hp with a good camshaft and good headwork, still with a carburettor. It will have taken some carefull jetting. That would be a 112/113mph trap speed. Making more power than that with a carburettor is hard work. I don't know how much easier it gets with a big throttle or ITB's because I havn't tried though I think you've proven that there is a lot to be gained, just keep in mind that some of that efficiency will have come from your camshaft and cylinder head too.

it was a stupid title heading , but i agree with what ur saying itb v single throttle ,theres no way to prove either way .,and single is far more cheaper and easier to do but it does highlight that the car is getting benefit from removing that restriction .
what sort of trap speeds would i be looking for with the power made on sunday?

[Scoff]

not knowing how heavy your car is nor how exactly accurate the RR day was it's hard to say, i'll guess at 116mph

[Ashy]

I'll go upload your video now, give me ten mins.

Just tried to upload it and my PC crashed... Will upload it tommorrow.

[markey b]

what torque figures did it make with 270bhp mud?

[Mudslinger]

what torque figures did it make with 270bhp mud?

it was 260lbft @ 4,387 rpm which right away doesnt look right and is probably down to the wheel spin on the rollers when i get the boost spike to 30psi, isnt peak torque meant to be @ 5,250-5,500 rpm

anyway i quite liked this printout

can see its still making power right up to the limter which is way to early and the boost problem is really consistant not sure about the fueling maybe needs a bit tweeking

[dgdogz]

270





thats amazing

[Andrew Cooke]

your boost controller setup is horrible, very unstable. Not to take anything from you, but it looks like you're making 28psi at the peaks even at high revs, and the 270hp would be on a boost peak, the instability will be geting messed up with filtering in the software to make it all a bit confusing to look at.

It's still a nice looking power curve though

[Mudslinger]

yeah , we have a plan to fix the boost control , i new it was like this before i left , just didnt have the time to get it sorted , from what i can gather there is some sort of injector in the line between the ecu and the actuator and this is whats at fault ,it seems to be pulsing , if i cant get that fixed im just going to use a bleedvalve ,shame not to use the feature if its on the ecu though

Oh and by the way im still sticking with the figures from AVA as far as what power its making

[Andrew Cooke]

I found setting the boost controller up to be the hardest part of mapping my engine, it's one of those things that you can spend forever dicking with.

[michael tierney]

u will get a pulsating reading if u connect your map sensor to one runner only(even all four its not great)! to eliminate this i connected all my vac take-offs through 2 nissan Micra fuel filters (small alu type)doing this tends to dampen the pulses!!

[Cabbage]

Is it me or is that running very lean for a WOT run?