So I built this motor
02-22-2014, 05:09 PM
#1
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So I built this motor It's a 388 LT1 with the older afr 190's ported with matching ported intake 58mm TB. Lunati with 231/239 @.050 and .535/.550 110lsa running 10:1 compression Hooker super comps and a stock pcm with just a tune. It runs out good but it seems like it should be better than it is, thoughts?
02-22-2014, 05:29 PM
#2
It's a 388 LT1 with the older afr 190's ported with matching ported intake 58mm TB. Lunati with 231/239 @.050 and .535/.550 110lsa running 10:1 compression Hooker super comps and a stock pcm with just a tune. It runs out good but it seems like it should be better than it is, thoughts?
Slap a supercharger on it!
That or get those heads milled and run a thinner head gasket, for a performance NA LT1 you want 11:1CR MINIMUM, 12:1 + would be even better. Keep in mind this is a reverse cooled engine and it's not 1970 anymore. I think that is the main thing holding yours back, who tuned it also? Does it pull hard to 6700 RPM or so (mine does)? What valve springs are you running? 1.6 Roller rockers? 
02-22-2014, 05:47 PM
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It was to consider room for a power adder like a 200 shot. I did build the engine for it callies dragon slayer forged I beams and forged probes. The valve springs are 125 closed and 325 open
02-22-2014, 05:52 PM
#5
conservative....some of us like a S*&$ load of torque for a street motor 
....I like maximum power under the curve...not big top end pull and crappy low end, terrible driveability, and no use of 6th gear. The lift ratings is for stock 1.5 RR, not 1.6. I have absolutely zero loss of driveability, tons of torque from idle to 6700, NO cam surge at all.....can you say that about yours?? I seriously doubt it. OP's issue is compression, not cam.
02-22-2014, 06:14 PM
#6
You are getting nitrous mixed up with boost. A LT1 is NOT a regular small block chevy as some old timers seem to think. It is a fully forged bottom end right? There's plenty of people that have 12:1+ CR and run lots of nitrous, it does require a good tune however. Trending Topics
02-22-2014, 06:58 PM
#8
You could always sell them to somebody doing a forced induction build, and use the proceeds to buy some Advanced induction 200cc ported stock heads and make ~500hp, would be cheaper than buying a blower setup and all that goes with it. THEN throw on the N2O. Supercharger/turbo stroker would be cool, but pricey $$$.
02-23-2014, 02:50 AM
#10
That cam has 15 degrees of overlap. Not ideal for a supercharged app. 0 to 5 is what most aim for.
Your valve springs also lack enough seat pressure to control the intake valve with decent boost. Open rate isn't all that great either.
You also need to take the piston design into account with forced induction and nitrous. A thick top land and crown is necessary or you'll end up breaking off chunks or burning them. That's something you need to find out from Probe.
How thick is your head gasket now? If you can drop your compression you wouldn't need to be too dependent stuff like water/meth, intercooling, rich tuning, less timing, etc. The F1 is a serious blower and you won't be able to fully take advantage of it with that CR.
Your valve springs also lack enough seat pressure to control the intake valve with decent boost. Open rate isn't all that great either.
You also need to take the piston design into account with forced induction and nitrous. A thick top land and crown is necessary or you'll end up breaking off chunks or burning them. That's something you need to find out from Probe.
How thick is your head gasket now? If you can drop your compression you wouldn't need to be too dependent stuff like water/meth, intercooling, rich tuning, less timing, etc. The F1 is a serious blower and you won't be able to fully take advantage of it with that CR.
02-23-2014, 08:27 AM
#11
Compression doesn't care about displacement, and the cam is not THAT conservative....some of us like a S*&$ load of torque for a street motor ....I like maximum power under the curve...not big top end pull and crappy low end, terrible driveability, and no use of 6th gear. The lift ratings is for stock 1.5 RR, not 1.6. I have absolutely zero loss of driveability, tons of torque from idle to 6700, NO cam surge at all.....can you say that about yours?? I seriously doubt it. OP's issue is compression, not cam.
conservative....some of us like a S*&$ load of torque for a street motor ....I like maximum power under the curve...not big top end pull and crappy low end, terrible driveability, and no use of 6th gear. The lift ratings is for stock 1.5 RR, not 1.6. I have absolutely zero loss of driveability, tons of torque from idle to 6700, NO cam surge at all.....can you say that about yours?? I seriously doubt it. OP's issue is compression, not cam.
Last edited by Rob94hawk; 02-23-2014 at 08:32 AM.
02-23-2014, 08:54 AM
#12
02-23-2014, 09:15 AM
#13
I notice you don't mention zero loss of driveability at low RPMS; a smaller cam with more cubes to work with lets you have your cake and eat it too! Mine starts making 350 lb/ft RWTQ at just 2600 RPM....over 400 lb/ft of torque by 3800 RPM and has a very FLAT torque curve a 350 with a big cam could only dream of....as mentioned, not everyone wants a soft low end just to chase big numbers on the top end. I wanted to build a fast street car with power everywhere, not a dyno queen
I have no problem daily driving with an M6/3.42's. Granted I only get 350 lb/ft @ 3400 maxing out at 380 after dropping off at 5800 I would expect a bigger cube engine to come up with bigger torque #'s. But for 'just a 350' my curve is quite flat. And I'd like to thank Loyd Elliot for that.
Last edited by Rob94hawk; 02-23-2014 at 09:40 AM.
02-23-2014, 10:57 AM
#14
Last comment about our cars cause we're hijacking this guys thread.
I have no problem daily driving with an M6/3.42's. Granted I only get 350 lb/ft @ 3400 maxing out at 380 after dropping off at 5800 I would expect a bigger cube engine to come up with bigger torque #'s. But for 'just a 350' my curve is quite flat. And I'd like to thank Loyd Elliot for that.
I have no problem daily driving with an M6/3.42's. Granted I only get 350 lb/ft @ 3400 maxing out at 380 after dropping off at 5800 I would expect a bigger cube engine to come up with bigger torque #'s. But for 'just a 350' my curve is quite flat. And I'd like to thank Loyd Elliot for that.
Point being: "different strokes for different folks" (you like that pun?
) I've seen your dyno graph, and you have a dip in torque starting at 4000rpm...the lunati cam on a 383 has a VERY flat consistent curve and better driveablility, no dips. 
Throw some 4.10's in yours already too, BIG improvement...I can poke around in 6th going 45mph at 1400rpm if I want and the LT1 is happy as can be and still pulls.OP's build will be just fine once he gets the CR up to par. THAT is my main point. No need to point him in the wrong direction (cam choice).
02-23-2014, 11:58 AM
#16
Good point....I tried to run some slightly used comp cams triple valve springs that came on my ported heads with that cam to save a few bucks and had valve float above 5800 RPM 
, replacing with some Lunati voodoo ovate beehive valve springs matched to the cam solved it.
OP, what springs are you running?
, replacing with some Lunati voodoo ovate beehive valve springs matched to the cam solved it.OP, what springs are you running?