Lt1 head advise
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Lt1 head advise Looking for advise on heads for 383.I have been talking to loyd Elliot on the trick flow 23 degree heads,and the price is really good ,not much more than porting the stock ones.my castings are the 561,witch Im told have thinner walls for extensive port work..I have been researching a lot and really torn on my best opinions for this build.i have a buget of about 2k for heads.This is not guna be a daily,just a street strip car.trying to get close to 500rwhp..The plan is 11.5 compression,383 rotating 4340 kit -5cc pistons and around a 230/244 110lsa solid roller,ported Lt1 intake 17/8 long tube headers, 4inch y pipe to single muflex exhaust,58mm throttle body.....I have all this except cam and the heads Im asking for advise on...PS if any one has some good heads for sale let me know thanks.
The trickflow heads have a much higher potential than the LT1 stock castings. Going off of memory I believe max effort on both you're looking at about 30cfm different between the two, plus you have a brand new casting on your motor.
The problem with the trickflow heads are making sure to account for the fact that they have 62cc combustion chambers compared to factory heads which range from 52-55cc. This will drop the compression all things being equal, but it can be taken care of with things like decreasing the relief in the piston, machining the deck height, milling down the heads, thinner gaskets, increased stroke/bore, etc. It's one of the biggest mistakes people make when they use aftermarket castings and end up with a motor with less compression than stock.
Another thing you can do is talk to Lloyd about using the Trickflow 21 castings which have smaller combustion chambers and a decreased valve angle. He will know what's best for your setup though.
http://www.ellweinengines.com/ has great examples of engine dyno's of different LT1 setups
The problem with the trickflow heads are making sure to account for the fact that they have 62cc combustion chambers compared to factory heads which range from 52-55cc. This will drop the compression all things being equal, but it can be taken care of with things like decreasing the relief in the piston, machining the deck height, milling down the heads, thinner gaskets, increased stroke/bore, etc. It's one of the biggest mistakes people make when they use aftermarket castings and end up with a motor with less compression than stock.
Another thing you can do is talk to Lloyd about using the Trickflow 21 castings which have smaller combustion chambers and a decreased valve angle. He will know what's best for your setup though.
http://www.ellweinengines.com/ has great examples of engine dyno's of different LT1 setups
Last edited by myltwon; May 2, 2019 at 06:50 AM.
Looking for advise on heads for 383.I have been talking to loyd Elliot on the trick flow 23 degree heads,and the price is really good ,not much more than porting the stock ones.my castings are the 561,witch Im told have thinner walls for extensive port work..I have been researching a lot and really torn on my best opinions for this build.i have a buget of about 2k for heads.This is not guna be a daily,just a street strip car.trying to get close to 500rwhp..The plan is 11.5 compression,383 rotating 4340 kit -5cc pistons and around a 230/244 110lsa solid roller,ported Lt1 intake 17/8 long tube headers, 4inch y pipe to single muflex exhaust,58mm throttle body.....I have all this except cam and the heads Im asking for advise on...PS if any one has some good heads for sale let me know thanks.
1. You'll need more cam;
2. You'll need better heads;
3. You'll need more compression.
FWIW.....
KW
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I didn’t realize till now that the 23 degrees are 65cc ya that’s not guna work I did talk to loyd on the 21 degrees are like a 55cc.. I know to get close to we’re I want with it,is guna need 11 to 12 compression and a solid roller.i was also thinking about the afr street heads.what do you think of those?
I wouldn't waste time on any AFR below the 210's and even then I would only get the 210 in the Competition Port. At that point though you're looking at $2700 worth of cylinder heads, which if you want to do it properly you "should" have the LT4 intake (people have gotten by with either welded up LT1 intakes and unmodified LT1 intakes) which adds another $600. So now you're at $3300 worth of top end, which puts you $1500 over the LE Trickflows.
Also all of this isn't accounting for the fact that a lot people think the AFR springs are underspec'd so you might be looking at another $200-300 for new valve springs which sets you $1700-1800 over the Trickflows...which means good news you can buy two sets of the Trickflow heads now for the price of a properly setup AFR top end. Or take the savings and buy a matching cam for the Trickflow heads from Lloyd and a budget forged rotating assembly.
Also all of this isn't accounting for the fact that a lot people think the AFR springs are underspec'd so you might be looking at another $200-300 for new valve springs which sets you $1700-1800 over the Trickflows...which means good news you can buy two sets of the Trickflow heads now for the price of a properly setup AFR top end. Or take the savings and buy a matching cam for the Trickflow heads from Lloyd and a budget forged rotating assembly.
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From: Euless, TX
I think the OP is right in line with both compression and cam. Might be better to get a little closer to 12:1 if possible but going from 11.5 to 12:1 is probably less than 2% difference in output and may cause octane sensitivity in tuning.
Cammed properly and built equally a 383 is going to give toughly 10% more power than the same .030 over 350.
With the size cam he has stated even if he were to use something like Lloyd's LE3s he would still end up in the 470 rwhp area.
My 9.6:1 350 made 395 rwhp @ 6,000 rpm through a 4L85E in 2nd gear and 5.13 geared GM 10.5" rear. Cam measured 218/228 @ .050 on the degree wheel and with the 1.7 rockers netted 0.578/.578" lift. Heads are 210cc intake port with 2.02/1.60 valves. Flow 291 cfm @ .500 and 299 @ .600. Exhaust flow was like 193 and 199 at the same lifts. I run Thorley Tri-Y headers into the factory 3" dual pipes to the muffler and a dual 3" in/single 4" out muffler. Intake is a marine crossram MPI intake but it is about to be a marine dual plane MPI intake with a 102mm TB using a carb to 102mm elbow.
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I have been emailing with loyd on the trick flow 21 degrees,with double springs fully ported they will run around 2100,he also told me me would knock of 200,300 for my old 561 castings.i have found a set of 643 castings to maybe buy to have ported.i have also talked with Eric Bradby at e.b porting and from what I have read on other forums about him he knows his shixxxxxxx,and really kno’s How to make power.. so with that ,I’m not leaning either way yet.The stock casting do make power.i don’t want to cheap out and do it with best I can afford..my friend owns a machine shop and engine dyno and he pulls 550 fwhp with 10.5 355 ci solid roller motors with big Chevy cast bow tie vortex heads.. if anything would hold it back from being close to 500 rwhp i think would be intake and tuning...I just looking to try n get close as possible,n make good hp and toque numbers and be somewhat streetable and driveable.sorry for long reply
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