Race Engine Built Question
11-09-2007, 10:23 AM
#1
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Race Engine Built Question
Good Day!
Got my quote from the heads guy - he will machine away 16 valve seats to fit the 968 intake valves, 3-angle cut the 16 exhaust seats and change the valve seals on all 32 valves for US$240
Works starts in 2 weeks
That set me thinking - how much can I take away from the heads to raise the compression of the engine. The stock 10.4:1 seems a bit tame when you compare it to modern race engines.
Also would I need to notch the GTS pistons for the 968 valves or the original cut-outs would be enough?
Many thanks in advance
Alex
Got my quote from the heads guy - he will machine away 16 valve seats to fit the 968 intake valves, 3-angle cut the 16 exhaust seats and change the valve seals on all 32 valves for US$240
Works starts in 2 weeksThat set me thinking - how much can I take away from the heads to raise the compression of the engine. The stock 10.4:1 seems a bit tame when you compare it to modern race engines.
Also would I need to notch the GTS pistons for the 968 valves or the original cut-outs would be enough?
Many thanks in advance
Alex
11-09-2007, 10:40 AM
#2
Three Wheelin'
Wow, your shop is cheap. You wont be able to machine your heads much, it's not a good way to look for compression, custom pistons is. In your case the intake valves are so close to the flat surface that you couldn't cut much at all before you hit the valve seat, the larger valve is even closer.
11-09-2007, 11:03 AM
#3
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Unless you have money to spare, I'd say spend the money on custom cams in place of increased compression. Like Mike said, new pistons is always preferable to shaving the heads/block for increasing compression.
11-09-2007, 11:17 AM
#4
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I will be fitting sharper cams - my old GT cams are the starting point. I just hoped that I can get a bit more from shaving the heads too.
Sterling, thanks for the information on piston notching. Would my heads guy be able to do the work?
TIA,
Alex
11-09-2007, 11:20 AM
#5
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use a dremel to take 1mm off the piston cuts. again, they dont even come close under normal operation. the cuts are more for moving the cams around when the piston is stuck at TDC or near TDC. (and a little bit of clearance if you break a timing belt and catch it in time 
)
)
11-09-2007, 12:23 PM
#6
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use a dremel to take 1mm off the piston cuts. again, they dont even come close under normal operation. the cuts are more for moving the cams around when the piston is stuck at TDC or near TDC. (and a little bit of clearance if you break a timing belt and catch it in time )
)Next question - would I need to enlarge the intake ports on account of the bigger valves?
Alex
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11-09-2007, 01:32 PM
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11-09-2007, 02:09 PM
#9
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we are talking Bulgaria - average monthly wage there is around $750, so my $240 for a valve job is actually pretty good money for them I guess. I give him the heads as they are, with the new Kolbenschmidt valves in their boxes, and collect the ready heads 3 days later. Sweet!
Back on topic - do I need larger inlet ports? The cost will be extra - something like another $200...
TIA,
Alex
11-09-2007, 03:18 PM
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11-09-2007, 03:22 PM
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11-09-2007, 04:09 PM
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11-09-2007, 04:47 PM
#14
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Dude here
Take a lot for me to take any offense. Especially on the Internet!
I hope the Bulgaria guy does a good job and sets up the heads correctly. If he does, then what a deal!
Now what are you going to do to take advantage of those bigger valves?
Take a lot for me to take any offense. Especially on the Internet!
I hope the Bulgaria guy does a good job and sets up the heads correctly. If he does, then what a deal!
Now what are you going to do to take advantage of those bigger valves?
11-09-2007, 05:38 PM
#15
Alex no need to increase the port size with your current build, all the headwork should be is a nice blend to the seats, that is throuting and blending. Did those valve from Pelican end up being KS?
Greg
Greg