T-body is too big. drop down to a 65 or 70mm max.

Pete.

I've managed 157rwkw with ho intake and e7s. Only the mods listed in sig.

I would have been happy using a 65mm but the mechanic/tuner wanted a 75mm. I'll ask him again about it. I think its overkill.
As for rwkw mine stock could only muster up 122rwkw with just the ecu and exaust so you have done well. Every dyno's different thats just the figure the car got on the day.

Asked about the 75mm tb and my tuner cant see how it can be taking power away, as long as its tuned right the ecu will match fuel to the air coming in. XR9UTE I'd like to know why you think it robs power.

Oversized throttle body would'nt make that much of difference, as its only feeding the plenum anyway. Its not like having oversized intake runners, ports or valves, where the loss of air velocity (momentum) is critical to cylinder filling after BDC.

Yeah 65mm would be better for that setup. TBs are relatively cheap. Can't hurt trying and seeing for yourself eh?

Stock Cobra uppers can go a 70mm TB without needing to be enlarged. That's a fair bit of volume for a 5L.

Still would like some hard facts on why its robbing power on my motor. I've got a 65mm tb sitting in the shed but untill i see proof on why it is better thats were it will stay.

I will have a crack at what they are trying to get at.

The analogy of it is, (a much exagerated version) its like the difference between sucking water through a straw then trying to do the same with bit of 20mm hose. You may lose a little bit of bottom end throttle response, thats all. Nothing really to worry about.

Better to be too big than too small I reckon.

Willing to seperate with the 65mm T/B?

Willing to seperate with the 65mm T/B?.

Nah not at the moment, Ive got a xf one if thats any help but i keep thinking your already using one .

No worries mate. XF one no good. Not for me but for a mate who is doing a top-end upgrade to an EL XR8. Heads have been sourced, now after Explorer/cobra manifold and 65mm T/B.

Too large a t-body has a similar effect to too large a carby. Loss of velocity results in slower cylinder filling and therefore less torque and a drop in power. And, lets be clear; the entire inlet tract has an effect on velocity....Not just everything after the t-body.
Many many tests have proven this over the years.
A general rule of thumb is for a basic mild 5.0L(in the 220-280rwhp range) is 65mm or 70mm but no bigger. A 75 will result in less area under the curve on these engines. Less area under the curve results in slower acceleration.
75mm plus t-bodies should be reserved for 300+ rwhp 302's or 330+ ci engines.
As an example. An ED sprint I worked on was fitted with TW heads,street heat intake, a 2031 cam,pacemakers and 2 1/2" twin. The guy used a holley 75mm t-body(and I'm sure the only reason was that it was polished). At the track it did 14.4's and after some TwEEC'n 14.1's. I suggested switching back to the stock 65mm, he complained but then did the switch. It went 13.9's with no other changes. The next step was to switch back to the sprint intake which I think is better than a street heat and it went 13.7's.
What's ridiculous is that he later switched back to the 75mm because someone p****d in his pocket saying it would work better with the 3.7 gears he installed.....it never did better than 14.5's!

Pete.

Point taken. Might swap it over and do a power run to find out then again i might just leave it on till the next lot of work is done then try both.

so in the 5.6 the T/B is an 82mm is this an overkill??