Looking for cam options for my TT427!
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FormerVendor
iTrader: (3)
Joined: Aug 2002
Posts: 622
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From: Albany, New York
Looking for cam options for my TT427! I have finally gathered all of my shortblock parts for the TT427 motor going into my Pro Touring 62' Chevy 2 and want to get a cam going.
The motor is a 8.6:1 compression motor fed with two T60-1 (T4/T4) turbos setup for 15-20 lbs of boost. All this boost is getting stuffed through a sheet metal intake and exhaust is a healthy 3". Heads are the AFR 225 with Inconnel valves and good valve job
I was thinking of a cam with 242/238 on 115 LCA and lift in the .610" range. Anyone else with a similiar setup?? Open for opinions!
The motor is a 8.6:1 compression motor fed with two T60-1 (T4/T4) turbos setup for 15-20 lbs of boost. All this boost is getting stuffed through a sheet metal intake and exhaust is a healthy 3". Heads are the AFR 225 with Inconnel valves and good valve job
I was thinking of a cam with 242/238 on 115 LCA and lift in the .610" range. Anyone else with a similiar setup?? Open for opinions!
Teching In
Joined: Dec 2003
Posts: 20
Likes: 0
From: Waterford MI
Alright now I will admit ls1's are not my expertise Im used to good ole sbc's. I knwo the ls heads flow well and so do the afr's but how well does the exhaust flow. What kind of i/e ratios are we looking at. Generally speaking with sbc's you want a much longer exhaust duration to allow the cylinder to sufficiently blow down and not loose too much to excessive pumping losses. They generally like big lsa's and also tend to like being retarded. Negative overlap is a good thing. Because of the backpressure created they like an early exhasut opening to allow the cylinder to blow down and then closing around tdc. But then opening the intake as much as 30* atdc proves to be a good thing since at tdc there still can be some pressure in the chamber because of the backpressure in the exhaust the cylinder cant vent to below this. So as the piston starts down the bore the pressure is decreased since volume increases so when the intake valve opens you dont have to worry about exhaust reversion. This means a cleaner, cooler intake charge. Even though the exhuast gases are still in the cylinder so they will still dilute it but since they arent blowing out the intake valve it keeps the charge cooler which aids in preventing detonation etc. But maybe Im old school and i need to learn more about these ls1's. Granted as exhaust flow increases something more like a single pattern cam can be used. But it requires very efficient exhaust port and seat work.
Josh
Josh
