The V8 Owners Forum -

Im using a 4.6 top hat cross bolted engine. It has ARP studs and the standard cast pistons. Im using de-compression plates and currently boost to 10psi, will be heading towards 15psi at the end of this month.

Its me with the 2x Td04 subaru turbos.

thanks for the replys guys mostly way above my head but Im enjoying learning. To start with the basics what is the squish band then?? How is that altered? I cc'd my old rover heads I have the Buick ones on the bench at home I will try and cc them tonight and see what they give, I will get a few pics...

Wotland wrote:Instead of decompression plate why not to open combustion chamber ? You should contact Paul Goodenough for porting.

How many CC's can you usually get from opening them out??

Thanks Mike, Thats the compression I had wrote down so nice to know it was right :-) Im about to get the larger valves from Dimitri on this site then let the build commence. Do you know anyone up to the job of sorting my heads?? I have never had any machining work done. Im guessing new seats and the...

Thanks Mike. I have the pistons in front of me now I reckon the crowns are 6mm thick according to my steel ruler. Sounds like I am best the develop the heads first in case they have been skimmed then I can come back with some true readings. What do you think about de-comp plates?? I liking the ideas...

Thanks for the reply mike you are baffling me lol I am currently around 8.0 on my engine thats with original TVR heads but I am using de-compression plates. Some people like them some dont it was a mixed review when I got them. But they have stood up fine at 10psi now for 3000+miles. They are 1.5mm ...

Hi Sidecar I see what you are saying about valve clearance, but at this stage I think he needs to sort out a few other priorities first. Looking back, if he is going to make use of the 4.0 rods then he needs to deck the block by 30 to 35 thou, and get them bushed otherwise it is a case of looking f...

Hi, Im back thanks for all your help so far. My pistons turned up the other day they are the Ford Modular Manley 3.700" Forged Flat Tops It says the compression height is 1.220 on the box Is there a way of working out what rods I should use on my 4.6 engine? Either the 4.0 or 4.6 ones? I will b...

Why has water injection not been mentioned?? Surely the easiest to implement and with the advanced systems these days will give better results than an intercooler or chargecooler.

great reading Darkspeed. I have just found myself some Buick300 heads for my Turbo project that can supposidly flow pretty well with the bigger valves installed and ported. Fancy a porting job if I get the larger valves put it?? I was going to have ago myself but on speaking to a few people I could ...

I have found a set of the Ford Modular Pistons that are -24cc, can anyone work out the compression ratio with these with the buick 300 heads...again as earlier in the post would be using 4.0 rods in my 4.6 engine.

I dont have a clue lol My numbers keep changing...

Regards

Neal

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'...

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...

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

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