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What do you guys think? Seems kinda weak to me...guess I can always add a blower. Its roughly equivalent to a current gen LT1... The builder claims that it will gain 50hp when the engine gets broken in...that would be over 420ish whp. Guess that is nothing to sneeze at. This build seems pretty close to what folks like Golen get with their 383 crate motors.
Last edited by Jaye Bass; Aug 22, 2019 at 04:37 PM.
Decent numbers for a 383ci 180cc head mild cam LT1. 195 comp heads and more cam would really increase your numbers above 5600 rpms. Looks to have a lot of low end grunt!
Last edited by STL94LT1; Aug 23, 2019 at 02:13 AM.
I don't think you're going to gain 50hp with break-in. That's not typically how this goes with anything like modern engine building methods. I think your engine is making good power for the rpm at which the torque curve peaks. That is, it appears to be efficiently filling cylinders and running at nice peak cylinder pressures. It's just peaking at a pretty low rpm, and that does surprise me a little. I would have predicted the same torque peak at a little higher rpm, and a flatter torque curve, both of which would give you a higher peak power number. My 396 has a smaller cam (218/224, but with 108* LSA) and probably pulls this high or a bit higher, so I would have expected yours to go higher. What are the specs for this cam, beyond the .050 durations? Are they XFI lobes?
FWIW, you might be really, really happy with this engine. It's going to pull hard in the range where it operates the most, even on track. People will think it has more power than it does. That's how it goes with me. On a typical autocross course, even with the tall ZF6 ratios and stock 3.45 rear gears (2nd gear is good to 80mph), my car pulls hard. So this may may be great for you.
I don't think you're going to gain 50hp with break-in. That's not typically how this goes with anything like modern engine building methods. I think your engine is making good power for the rpm at which the torque curve peaks. That is, it appears to be efficiently filling cylinders and running at nice peak cylinder pressures. It's just peaking at a pretty low rpm, and that does surprise me a little. I would have predicted the same torque peak at a little higher rpm, and a flatter torque curve, both of which would give you a higher peak power number. My 396 has a smaller cam (218/224, but with 108* LSA) and probably pulls this high or a bit higher, so I would have expected yours to go higher. What are the specs for this cam, beyond the .050 durations? Are they XFI lobes?
FWIW, you might be really, really happy with this engine. It's going to pull hard in the range where it operates the most, even on track. People will think it has more power than it does. That's how it goes with me. On a typical autocross course, even with the tall ZF6 ratios and stock 3.45 rear gears (2nd gear is good to 80mph), my car pulls hard. So this may may be great for you.
I was thinking this too. 427ftlb at 3500 is definitely going to put a smile on your face and will be very useful for autox
Otoh, it won't feel as fast for 1/4 mile racing
How well is the car running in partial throttle conditions? Is the Holley system all dialed in already?
I was thinking this too. 427ftlb at 3500 is definitely going to put a smile on your face and will be very useful for autox
Otoh, it won't feel as fast for 1/4 mile racing
Yep, the name of the game for drag racing is average power. The "feel as fast" thing is deceptive though, because if you move the torque curve higher in rpm but the peak remains the same (and make no other changes), then you will not feel any harder pull in each gear. You'll just feel the same amount of acceleration but at a higher road speed in each gear. That will show up in the times and trap speeds, as long as you wait later to upshift. But it might not feel more impressive. Alternatively, if you made that change to the engine and then used shorter rear gears, you would feel a harder acceleration pull. Ideally, you want it geared it top out in 4th gear in the traps. I can't recall offhand how the stock gearing looks for that.
But if you move shorter rear gears - say, 4.11 - then you might run out of 2nd gear on a lot of autocross courses, depending on where your redline sits and how the courses are typically laid out in your neck of the woods. Locally, we have a fair number of courses that exceed 70mph (in my car), so I have no desire to run shorter gears for this. So you may have to manage the tradeoffs. Part of this will end up as a trial-and-error exercise.
How well is the car running in partial throttle conditions? Is the Holley system all dialed in already?
I think you have my car confused witho someone else's. I run the stock PCM system, except that in my 96 I'm mostly using a 94/95 computer (pretty much the same as the 96 but no OBD2 tests, and it can be set up with BLM locked so it will never run too lean at WOT). It was well tuned by the previous owner, and it runs beautifully in all conditions. I daily-drove this car for three years in all weather, and drove it on two 300mi trips. It has always been perfect, including good mileage and great throttle response.
Yep, the name of the game for drag racing is average power. The "feel as fast" thing is deceptive though, because if you move the torque curve higher in rpm but the peak remains the same (and make no other changes), then you will not feel any harder pull in each gear. You'll just feel the same amount of acceleration but at a higher road speed in each gear. That will show up in the times and trap speeds, as long as you wait later to upshift. But it might not feel more impressive. Alternatively, if you made that change to the engine and then used shorter rear gears, you would feel a harder acceleration pull. Ideally, you want it geared it top out in 4th gear in the traps. I can't recall offhand how the stock gearing looks for that.
But if you move shorter rear gears - say, 4.11 - then you might run out of 2nd gear on a lot of autocross courses, depending on where your redline sits and how the courses are typically laid out in your neck of the woods. Locally, we have a fair number of courses that exceed 70mph (in my car), so I have no desire to run shorter gears for this. So you may have to manage the tradeoffs. Part of this will end up as a trial-and-error exercise.
I think you have my car confused witho someone else's. I run the stock PCM system, except that in my 96 I'm mostly using a 94/95 computer (pretty much the same as the 96 but no OBD2 tests, and it can be set up with BLM locked so it will never run too lean at WOT). It was well tuned by the previous owner, and it runs beautifully in all conditions. I daily-drove this car for three years in all weather, and drove it on two 300mi trips. It has always been perfect, including good mileage and great throttle response.
Question was to OP who is running Holley EFI and custom wiring harness. Im actually waiting for the right time to ask OP for his builder's name to get a quote for just the wiring harness
Question was to OP who is running Holley EFI and custom wiring harness. Im actually waiting for the right time to ask OP for his builder's name to get a quote for just the wiring harness
Question was to OP who is running Holley EFI and custom wiring harness. Im actually waiting for the right time to ask OP for his builder's name to get a quote for just the wiring harness
I am going to pick up my car tomorrow. The builder sent me the following caveat on engine operation. I have this camshaft; COMP CAMS 224 230 DURATION .503 .510 LIFT
The engines camshaft duration requires specific driving techniques, keeping the engine
rpm at or above 2200 when the engine is loaded. Spark plug fouling can be expected if
the engine is started for short intervals and shut off before engine operating
temperature is above 196 degrees. Prolonged idling will also cause spark plug fouling
and engine oil dilution which can damage engine bearings and piston skirts.
The engine rpm should not exceed 3500 rpm after sitting in gridlocked traffic until the
engine temperature has dropped below 210 degrees. Piston damage can occur if the
engine is left idling for a long period of time, a/c on and then wide open throttle occurs
without allowing the engine temperature to stabilize at or below 200 degrees.
Engine oil pressure should maintain 15-20 psi at idle with 200 degree engine
temperature, oil pressure should rise to 60 psi at 6000 rpm using 10W30 engine oil.
Any thoughts? Is this excessive CYA or real concerns?
Last edited by Jaye Bass; Nov 19, 2019 at 12:02 PM.
To me a little cya , but it sounds like tuning required. Cam will effect vacuum or MAP, low reading can cause overfueling. I was talk to tuner or study diy tuning.
Basically what I'm reading between the lines is that he's got your car running really rich in anything except WOT conditions. IOW, it's not tuned very well. Your cam isn't too huge, so it should be able to operate in all normal phases (what's the LSA or overlap?). I have a cam with less duration but 108 LS and a lot more lift and aggressive ramp rates (so it has significant overlap), and I can idle all day and lug ~1600rpm in 6th gear (about 60mph) on the highway forever. I can also do stop-and-go traffic for as long as I can tolerate it, but the engine will always tolerate it.
To me a little cya , but it sounds like tuning required. Cam will effect vacuum or MAP, low reading can cause overfueling. I was talk to tuner or study diy tuning.
Originally Posted by MatthewMiller
Basically what I'm reading between the lines is that he's got your car running really rich in anything except WOT conditions. IOW, it's not tuned very well. Your cam isn't too huge, so it should be able to operate in all normal phases (what's the LSA or overlap?). I have a cam with less duration but 108 LS and a lot more lift and aggressive ramp rates (so it has significant overlap), and I can idle all day and lug ~1600rpm in 6th gear (about 60mph) on the highway forever. I can also do stop-and-go traffic for as long as I can tolerate it, but the engine will always tolerate it.
That is what I thought. The delivery has been delayed for two weeks because of tuning issues that he has admitted to, that by the way sound like overfueling/rich conditions. Then I get a call Monday night saying that it was all fixed by changing plugs. I'm just going to take it...hoping I make it home...and get it to a local tuner.
Last edited by Jaye Bass; Nov 20, 2019 at 09:18 AM.
Basically what I'm reading between the lines is that he's got your car running really rich in anything except WOT conditions. IOW, it's not tuned very well. Your cam isn't too huge, so it should be able to operate in all normal phases (what's the LSA or overlap?). I have a cam with less duration but 108 LS and a lot more lift and aggressive ramp rates (so it has significant overlap), and I can idle all day and lug ~1600rpm in 6th gear (about 60mph) on the highway forever. I can also do stop-and-go traffic for as long as I can tolerate it, but the engine will always tolerate it.
