The V8 Owners Forum -

Hi, I have a TVR Chimaera which I have converted to 4.6 Twin Turbo. Im using standard 4.0 heads and are struggling to get me past 370bhp, making great torque 490lbft.

I now have in my garage a set of Buick 300 alloy heads, they seem really good condition I want to use these as from my research they are a good starting point.

Ive tried to do as much as possible on the build myself so any pointers on how to get the best out of these heads on a budget.

I have seen you can get 1.775 inlet and 1.50 exhaust valves in but they require new seats. I have found the part numbers but cant seem to actually find the parts.

Can anyone recommend anyone that could install these for me and maybe porting?? I dont mind getting my hands dirty and like to talk in pound notes

Thanks

Neal

Just out of interest , what size/type turbos are you running and what boost?

Cheers Denis

Im using 2x Subaru Td04l turbos at 9 psi at the moment.

I assume you are running low compression pistons and if otherwise it's a standard 4.6, then 370 BHP is about right if not good for 9lb boost.

When you go for the better heads I would suggest that the fresh air inlet be increased in diameter as going by your pictures, they look restrictive to me.
Cheers Denis

Hi,

I should have some valves but need to check.

Back to you asap

Wotland wrote:Hi,

I should have some valves but need to check.

Back to you asap

Ohh sounds good, so you might be the person I need to ask many questions too now then

Neal,

Bear in mind that the 300 heads have a 54cc combustion chamber as standard compared to the 28cc 4.6 heads so you are looking at a massive reduction in compression ratio unless you change pistons.

You can machine the 300 heads to reduce the chamber size to approx 47cc.

The oversize 4.6 modular Ford forged pistons are good value but you will have to bush the small end on the rods or a cheap fix would be to use Rover 4.0 pistonswith a 13cc dish if they will stand up to your usage.

What pistons do you have at the moment?

Kevin.

Hi
The ford mod flat toppers and 54 cc chambers on 4.6 litres should give a usable Cr for a turbo set up if you pop the pistons about 20to 30 thou down the bore, it should give you a CR of about 9.5 to1 which would be good up to about 8 to 10 lbs boost and with heads that flow properly that should give alot more power.
Bets regards
Mike

CastleMGBV8 wrote:Neal,

Bear in mind that the 300 heads have a 54cc combustion chamber as standard compared to the 28cc 4.6 heads so you are looking at a massive reduction in compression ratio unless you change pistons.

You can machine the 300 heads to reduce the chamber size to approx 47cc.

The oversize 4.6 modular Ford forged pistons are good value but you will have to bush the small end on the rods or a cheap fix would be to use Rover 4.0 pistonswith a 13cc dish if they will stand up to your usage.

What pistons do you have at the moment?

Kevin.

Hi Kevin,

At the moment I am using standard 4.6 pistons but with a de-compression plates to drop it down to around 8.0's. Im hoping now to be able to leave the plates out. Do you know roughly what this would make the compression ratio? standard 4.6 large journal engine, with the 54cc chambers. I have yet to measure when I get my workshop finished!

Edited: Sorry just noticed you mentioned FORGED pistons ....tell me more, tell me more

Hi
5.4 litre ford mod pistons, as I posted earlier (on another thread http://www.v8forum.co.uk/forum/viewtopic.php?t=9528) Ian Stewart is using them in his current build they are forged and very light. Looks like some people do them with a 7cc or 11cc dish which could also be usefull. A quick hunt around gets a price of between $500 and $700 but I think Ian found them for about half that on E-bay I will have a look later.
Best regrads
Mike

4.6 pistons and 54cc Buick heads with composite gaskets would give a very low CR.

I went the other way on my NA 4.6 - skimmed 080 off the heads, welded up the chambers to get them down to 37cc and used tin 300 gaskets.

Ended up with about 9.2:1 I think which is ok for the crap fuel we get here these days.

Neal,

300 heads, standard 54cc chamber and 4.6 pistons = approx 7/1 CR.

Pistons from the same source as Ian for an even better price.

http://cgi.ebay.com/ebaymotors/ws/eBayI ... MEWAX%3AIT

Will give approx 9/1 CR slightly less if you need valve cut outs.

Kevin

Thanks Kevin.

This certainly seems a route I will be taking now, might as well have the forged pistons in there at that price. As far as fitting these to the rods what are my options??

Just need to get my Buick heads ported and bigger valves fitted now.

Seems you can those pistons with different cc's now I thought I ideally wanted around 8.0 's on the compression for turbos??

Thanks for your input people really liking this forum so far, I come from pistonheads and this has so much more knowledge first hand and friendly people

neal1980 wrote:Thanks Kevin.

This certainly seems a route I will be taking now, might as well have the forged pistons in there at that price. As far as fitting these to the rods what are my options??

Just need to get my Buick heads ported and bigger valves fitted now.

Seems you can those pistons with different cc's now I thought I ideally wanted around 8.0 's on the compression for turbos??

Thanks for your input people really liking this forum so far, I come from pistonheads and this has so much more knowledge first hand and friendly people

Neal. I believe you need Rv8 4.0 con rod with the Forged pistons Ian Stewart used. This is to get the correct compression height. I don't know what thickness sleeve was used to match the pistons to the rods small end or if he made them fully floating or not.

Hopefully Ian will come in on this with some info.

Cheers Denis

I am sending you a PM.

Neal,

Yes 6.111" 4.0 Rods are required, will leave the piston 15 thou. down the bore which is a liitle less than I thought so with standard composite gaskets the CR will be approx 9.5/1 so you will probably need to use thicker cometic gaskets which you can order to required thickness.

You should be able to pick up a set of 4.0 rods fairly cheaply and have them bushed with sufficient clearance to make them fully floating.

Kevin.