The V8 Owners Forum -

I think I've maxxed this system out now.
Even though I chopped my small collectors out to 2.5". I still had back pressure issue when running the 200 shot. (long story, but I know it was a problem)

So I've now cut the mutha's up again and stuck 3" tails on. Now when I look up the collector pipe I can see all four primaries with just a tad of the outside edges obscured by the collector tail. The 2.5" tails blocked off nearly half of the primary pipes.

I've also removed as much metal as I can from the exhaust ports with my limited tooling. I've nibbled metal away to make sure the the free area in the ex ports is bigger than the free area of the ex valve seat opening in the chamber and it gets progressively bigger up to the port flanges. That's about all I can do with these stock Range Rover EFI heads without forking out for bigger valves to be fitted in the ex side.

I've also got another 80 thou of valve lift from the cam as I had the guides trimmed down a touch.

So the stock engine is now tweaked as far as I reckon it can be with just a slightly wilder cam and stock sized forged pistons.

I know she is breathing better now because she needed and extra 3/4 turn on each idle screw on the Weber 500 to get her to settle at a smooth idle.

I do hope that 10.99 is on the horizon......I've been slowly chipping away for years now. 12.4 seconds PB back in late 2006. 11.26 last year with this setup + a 200 shot of gas. But then the stock pistons broke after 40 passes.

Bear in mind that this is a 90,000 mile Range Rover 4.6 that has not yet been rebored. I've broken and melted 4 pistons since May 2007 and just scraped the ally out of the bores with a stanley blade.
I'm also still using my stock MGB V8 diff and shafts. The engine still has its original crank and rods too.
So here a pic of my latest lash up.

Very nice Perry! Can you get 3" silencers or are 2.5" generally the biggest readily available (looking at real steel & not that you need them)? What size HT leads are you using and have you considered putting a vacuum pump on the crankcase breathers? Actually using your system (open headers) you could just put an evac system in (normally with mufflers you risk putting pressure into the crankcase instead of the other way round)

http://performanceparts.com/part.php?partID=1013

Some people have said its worth an extra 20 or so hp and you could do it in no time, the exhaust flow just draws the pressure out from the slanted pipes protuding into the tails...

TC

You can get up to 5" bore exhaust parts. If you get off on exhaust parts, take some bromide and check this out:
http://www.jetex.co.uk/website/jetexcus ... tparts.php

My Landie exhaust is built using the 2.5" stainless stuff, and it's very nice!

Chris.

Perry,

So your'e getting to the heavy breathing stage! I'm sure your going to crack a 10 sec. run this year.

If your going to North Weald June 14th I'll look forward to seeing it with the front end off the ground.

Kevin.

looking good young sir, And where did you get the pipe from as some 3"pipe will be needed for a couple of our cars,

I got the 3" fittings from Merlin Motorsports online. But dont buy the 3" "tight 90 degree bends". They are just elbows!!

I got a price from Motoserve for the 3" bends at £28 each. Merlin were £13 each.

If I dont break it again. I'll be at the Weald in June chaps.

Perry what headers do you have? (the ones that are wrapped up!) I'm thinking that I may need some similar ones to clear the side rails in my engine bay....

Tom!
They are RV8 style headers from MG Owners Club...