dizzyj

does anyone have pictures of what is done to a 951 head to make it work on a 3l? I always figured that the water passage needed to be routed out, but the bolts dont even line up.

is the water passage cut off and a new one welded on?

The other option is a 2.7 head, but I understand that the exhaust needs to be coated? any idea who/where can do that?

Thanks

Tom M'Guinn

The 104mm blocks used on the 2.7 and 3 liter motors have a different shaped water port at the front, which has only one bolt to hold it down, compared to the two-bolt port on the 2.5 blocks. A router (milling machine?) won't do the trick. I know Lindsey and others advertised modified 2.5 heads, and assume they were welding and decking to match the 104mm block port. The 2.7 head costs more but its combustion chamber is designed for the bore and has bigger intake valves. I use 951 exhaust valves and had the ports coated by Swain, though I'd say coating the exhaust is optional really...

dizzyj

thanks, I guess im wondering what it is that Lindsey and others do. if its just welding the port, would it be possible just to fill it with deck fill cement? does the port on the block also need to be welded?

If I have to send my head off, ill probably get a stage 2 treatment (while your in there). would it be better to spend the $$ on a 2.7 head? and if so, is it possible to port the intake manifold with a dremel?

appreciate the help

Thom

Porting the intake with a dremel will take an awful lot of time. I use a standard driller with the right head to grind aluminium.

Voith

I will go the same route, but will use 48mm intake valves from 2.7 head.

Haven't been able to find a single picture of this modification anywhere. Its a complete miss-match so I wonder what would be the best approach for this..

Welding both holes and route water trough rubber hose seems to be the most reliable solution.

Thom

Courtesy of the Lindsey Racing website :

Voith

Wow, beautiful, thank you.

What is the price of this modification @ LR?

333pg333

That doesn't seem to match the pics in Voith's post #5. Looks like the modification would require the water jacket to move further towards the firewall than they've done? Unless his comparison shots aren't actually lined up correctly from the front of the motor?

fred27

Patrick,
the original pictures show the mismatch between the 2.5L cylinder head and 3.0L block. The cylinder head mod involves welding a boss onto the cooling passage at the front of the head and then milling a new cooling passage to mate with the 3.0L block
regards

333pg333

Understood Fred. What I mean is that looking at the pics in Voith's post shows that the 2.5 Head looks shorter than the 3L block underneath it which makes the LR mod look incorrectly placed. I suspect that it's due to the head and block not lined up correctly in that pic.

dizzyj

Awesome. That's what I was looking for. Been all over Lindsey's site and missed those pics.

I think they charge very reasonably few hundred, so that is an option.

What are your thoughts of the 2,7 head for flow? Are the larger intake ports with the cost (say 1k or so)

gpr8er

I used a 2.7 head and did not coat the exhaust ports. It's a street car with 6k miles on the 3L motor now, no problems. IMO if you're going to spent all that money on a LR port job and mod I'd go for the 2.7 head instead. The intakes are sooo much bigger. And there's always the possibility of the ceramic flaking off the 2.5 turbo head at some point.

Voith

Head and cylinder are connected with dowel pins on those pictures so it is more or less lined up as supposed to.

2.5 water passage is moved to the rear for few centimeters



2.7/3.0 water passage is flat with the front of the engine



(these two pictures are from other threads)

Voith

Ive talked to factory mechanic that maitained 951 cup cars in germany and 959s in paris dakar and he told me that if I intend to go over 1bar boost I should use 951 head with ceramic in place.

Not sure why, but he said so.

Thom

Got 30k+ miles on my 2.7 head. No issues so far, even with 1.6 bar on a few recent occasions.

As Tom said the 2.7 combustion chamber is designed for a 104mm bore block, which is not the case of the 2.5 head.
A 2.5 head can certainly be modified in this direction but is it going to be more cost-effective, not sure.