The V8 Owners Forum -

So, after my original block going porous early 2011 I decided that rather than a rebuild with top hats I'd bite the bullet and go for a V8D high perf lump. Bottom end is x bolted, H beam rods, forged pistons, running 10.6:1 CR, bespoke cam somewhere between stealth and H404, original 500 heads to stage IV spec, Ford red top high flow injectors, ACT triple TB CF plenum, fully decatted, and MS2 fuel and ignition.... I've done about 13k miles since the rebuild three years ago, and on and off during this time I've lusted after the JE X over manifold with Jenvey TB's... Not cheap at just over 3k for the kit, but boy do they look good

Anyway, I've asked lots of folk and researched many places but no one can tell me (or guestimate) what torque and bhp gains I might see if I went ITB's. I understand the benefits of ITB's versus plenums, cross cylinder contamination, throttle response etc etc, but I just can't get any idea of potential numbers.....

Any experiences out there would be muchly appreciated..

Many thanks,

Chilli

I'd guess not very much since the limiting factor will always be the heads.

+40hp max..

Mgbloke get +40hp ovet the carb. 4.8litre
And i get +40hp over the siamese plenum. 5.2litre

Not sure about trible plenum, might less?

And why bought complete kit? Bought only an manifold and order separately those throttle bodies etc, you will save money..

Chilli your not going to get a fixed figure for this, over your triple I reckon 25+ as a guestimate

As a matter of interest, what does it do to the torque curve at the bottom end?

I'd say gains would be very camshaft dependent ?

ie you'd see more with a larger cam to try and spin it a bit harder ? But then that might require better valvetrain too ?

Expensive slippery slope, for relatively small gain per £££ spent.

I think if they had long runners, low rpm torque could only benefit. Short runners maybe less so.

But from other engine platforms, people say with they fit ITB's, it allows them to tame larger cams for better torque low down

Wowsers! Could get a centrifugal blower setup for that money?

Would work well with Higher CR due to boost rising with RPM?

Valid point.

A little bit of boost goes a long way !!

Fitting ITBs when you already have that setup is a complete waste of money IMO. Especially for the power gains, it's not sensible.

Give it a sniff of nitrous for £500 and 50bhp when you want that little bit more than the loud pedal gives currently.

If you're going to spend that sort of money on an RV8, go for some Wildcat heads instead. The ACT triple plenum is about as best an induction as you can get anyway. The current restriction on your engine are the heads, and always will be.

I do not see any point to use ACT triple plenum (If you have to buy it).
If under the bonnet is enought room for throttle bodies..

http://www.actproducts.co.uk/product/ti ... lenum-kit/
1500£ + vat

Buy Eales down draught manifolds for £495.00 + vat and set of Jenvey throttle bodies form ebay or staraight for Jenvey

http://www.johnealesroverv8.co.uk/7.html

Price is nearly same, and mutch better throttle control, better idle quality, emissions etc..

And for those wildcat heads, i still waiting impressive results for them.. automotivecomp/wild cat 5.0l 398hp engine is not impressive..

He already has the ACT plenum mate. Hence no need to buy the ITBs.

My point was he doesn't need to waste £3k on ITBs, but he could spend that money on wildcat heads. Anything is better than the rover heads!

So you mean that wild cat heads and ACT is good compo? Using stock ported inlet manifold?? Oh jeah..

Can you prove that anything inc wild cats are better than stage 4 ported rover heads? Where they are all?
Maybe in Race engine and using some silly cam, but not for street..
You can get 400hp and over if use rover heads.. Not ever seen wild cat engine (dyno graph) witch has got +450hp..

There's no mention of what inlet he's using, but its not expensive to get an inlet ported. I just think £3K could be better spent considering the act stuff is pretty good. Wildcats have their own inlet. The wildcats were designed to outflow stage 4 rover heads I dont need to 'prove' anything. But when youre getting to this level of spending on an RV8 its stupid money for little gains imo. I gave up on the rover years ago for that reason, no way could i afford to spend thousands and thousands for the output they give!

For the money a 350bhp+ rover is you can get almost double the power out of other v8s. A friend of mine just rebuilt his lexus v8 with new rods, pistons, home made plenum, big injectors, standalone ecu, a few other bits and a holset turbo, 800bhp on the dyno!

But we spoke RV8, not Lexus etc..

Also fiend of mine make ~1000hp 2.0 Ford MK2 turbo.. No need V8 to run fast 8.36s/257.99km/h 1/4mile