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Well, just fired my owner assembled 381 cu in (3.75 stroke/4.020 bore), 11.9 CR, GM 847 roller cam (.575/.595 lift), AFR Hydra Rev, CNCed LT4 headed engine tonight in the dark and with no mufflers!
What a sound and what a feeling. Talk about anxiety...did I forget to do that or this...do I really want to try to start it...might mean a whole lot more work!
What the heck!!!
Car definitely need idle tuning...wants to die when coming from a stop. Only drove it to seat the rings in.
Used SCAT 'kit' with 4340 crank, 4340 H-beam rods, SRP flat tops with my 54.6 cc chambers and Fel Pro gasket...11.9 CR on pump gas.
I haven't talked with SCAT, but I'm thinking I don't recommend them to anyone as their kit was a bunch of parts that would not work together...pistons seriously hit the crank counterweights.
This was the same engine that had the rods hit the camshaft by the way...that was not SCAT's fault, though.
This engine will be powering my 96 for the 2004 One Lap of America at end of April...and my F1 Supercar tires just showed up.
That's allot of compression. I always have a large can of Morroso 104+ octane booster in my tool compartment. Because we have a problem with stations that tend to make more money by having regular unleaded in all three pumps.
The problems is there is no regular or surprize inspections and the fines are so low if they get turned in and tested that the profit is worth the risk.
I agree and you can hear the sharpness of the exhaust note to prove it! I like it. It has a great lope although I'm not nearly finished tuning it.
I'm hoping for a large cam to bleed it down and reverse cooling LTX system to make it work. However for the roadcourse events I had planned to keep octane booster in the tank for that little bit of assurance.
So far I'm seeing very little knock although haven't gone past 50% throttle and 4500 rpm. I'm sure I will pull some timing out...especially for the fully heat soaked periods on the track at WOT!
Because we have a problem with stations that tend to make more money by having regular unleaded in all three pumps.
The problems is there is no regular or surprize inspections and the fines are so low if they get turned in and tested that the profit is worth the risk.
I haven't personally experienced this problem, but it's a great watch out for those of us running high CR and need the octane. My wife's 1995 Honda Accord and my 2003 Grand AM SC/T both run fine on the cheap stuff. I've goofed a few times and filled the Corvette with 87. The engine (383 I built in 1992) was clearly unhappy!
My compression is about 11.2 and with non emmission 3 inch true duals and race mufflers. It has a nice sound. Not a crackle, but that solid roller cam singing under the hood. I've never had a problem with our California max 91 octane. I also went with the thermal coated pistons and chambers.
My F1 SC's are 275's all the way around. I've decided to stay with 9.5 wheels to allow rotation and to switch back to my loved Nittos 555RII's.
Car got 26.8 and 27.3 mpg on recent 400 mile trip! Car didn't die was the big plus, but the mileage wasn't terrible. The cruise still needs work (spark tables) due to 'trailer hitching' as you go down the road. There might be some more left...:)
Re: 381 Fired for First Time Tonight! (SmokedTires)
I will admit that I was a wee bit disappointed at the mileage...only because the cars tripometer was spitting out 36 mpg for the trip! Course I do realize that the new injectors make that part of the computer unusable...
27 is pretty good. My HOT camed combo used to get 28 consistently.
Yesterday I finally decided it was broke in and hit the road course. 69 miles of 6/10's running. Car pulled quite well on the topend the few times I WOT it. It was impressive. I'm really quite happy that it didn't leak/blow/puke anything.