BLOWN LT4 RACE ENGINE - Any suggestions?
Thread Starter
Instructor
Joined: Aug 2004
Posts: 108
Likes: 1
From: Thousand Oaks CA
BLOWN LT4 RACE ENGINE - Any suggestions?
MORE INFO ADDED 11/17 8 A.M. SEE BELOW
With a terrible crunch and flaming oil spewing out the back, our 383 race engine died a glorious death on the track last weekend.
Although the autopsy isn't complete, the block is obviously trash. The lovingly ported LT4 intake and LT4 heads may be good though, so we will keep the top end, hopefully.
Our 92 C4 is STRICTLY ROAD RACE. We made 510 crank hp with the 383 at 11:1 naturally. I have listed all the parts below.
We might build an identical engine, but I thought I would ask for any suggestions here, because the folks on Corvette Forum have more knowledge about C4s than anywhere else in the world.
PLEASE POST ANY SUGGESTED CHANGES OR IDEAS! THANKS!
GM LT1/LT4 block casting 327 (bored to 383)
Pro-Gram 4 bolt billet main caps
Scat forged 4340 crank and billet H-beam connecting rods
SRP pistons
JE Plasma moly piston rings
Total Seal gapless rings
Clevite H-series rod and main bearings
Durabond performance cam bearings
Melling hi-vol oil pump M55HV
Canton oil pan
Comp Cams high tech chromoly pushrods
ARP fasteners
ADDITIONAL INFO ADDED 11/17:
Race-Prep in Bermuda Dunes built the motor, great guys, but legal hassles closed their shop recently
Very low oil consumption (after we fixed a leaking valve cover)
Ron Davis radiator with integrated oil cooler
Amsoil Syn2000 20w-50 (8 quarts)
For track use, oil slightly over-filled (about .5-1 quart)
Oil temps did run high (275-290) which concerned us, but were very stable at that temp
Oil pressure usually 80 psi
Canton Oil Pan is p/n 15-240T for road race ( http://www.cantonracingproducts.com/...road_race.html)
On dyno, ran to 7500 rpm with hp/tq curves still going up, no valve train chatter
We set rev limiter at 7000, shift light at 6500
On track, rarely ran over 6000, shift light never came on
(4th gear, 6000 rpm was about 125-130 mph)
Engine had about 5,000 miles street break in, then 2 hours autocross, 20-25 hours on track before failure
At time of failure, car had been on track about 40 minutes (outside air temps about 75 degrees)
Car came down slight elevation change, made tight 90 degree turn right into short straight when it failed.
(specifically at Buttonwillow, CA running CW leaving Grapvine toward Club Corner and Bus Stop)
The incident was recorded with in-car video, so we know for certain that RPM was (whoops, gotta check the tape again, I forgot exactly)
With a terrible crunch and flaming oil spewing out the back, our 383 race engine died a glorious death on the track last weekend.
Although the autopsy isn't complete, the block is obviously trash. The lovingly ported LT4 intake and LT4 heads may be good though, so we will keep the top end, hopefully.
Our 92 C4 is STRICTLY ROAD RACE. We made 510 crank hp with the 383 at 11:1 naturally. I have listed all the parts below.
We might build an identical engine, but I thought I would ask for any suggestions here, because the folks on Corvette Forum have more knowledge about C4s than anywhere else in the world.
PLEASE POST ANY SUGGESTED CHANGES OR IDEAS! THANKS!
GM LT1/LT4 block casting 327 (bored to 383)
Pro-Gram 4 bolt billet main caps
Scat forged 4340 crank and billet H-beam connecting rods
SRP pistons
JE Plasma moly piston rings
Total Seal gapless rings
Clevite H-series rod and main bearings
Durabond performance cam bearings
Melling hi-vol oil pump M55HV
Canton oil pan
Comp Cams high tech chromoly pushrods
ARP fasteners
ADDITIONAL INFO ADDED 11/17:
Race-Prep in Bermuda Dunes built the motor, great guys, but legal hassles closed their shop recently
Very low oil consumption (after we fixed a leaking valve cover)
Ron Davis radiator with integrated oil cooler
Amsoil Syn2000 20w-50 (8 quarts)
For track use, oil slightly over-filled (about .5-1 quart)
Oil temps did run high (275-290) which concerned us, but were very stable at that temp
Oil pressure usually 80 psi
Canton Oil Pan is p/n 15-240T for road race ( http://www.cantonracingproducts.com/...road_race.html)
On dyno, ran to 7500 rpm with hp/tq curves still going up, no valve train chatter
We set rev limiter at 7000, shift light at 6500
On track, rarely ran over 6000, shift light never came on
(4th gear, 6000 rpm was about 125-130 mph)
Engine had about 5,000 miles street break in, then 2 hours autocross, 20-25 hours on track before failure
At time of failure, car had been on track about 40 minutes (outside air temps about 75 degrees)
Car came down slight elevation change, made tight 90 degree turn right into short straight when it failed.
(specifically at Buttonwillow, CA running CW leaving Grapvine toward Club Corner and Bus Stop)
The incident was recorded with in-car video, so we know for certain that RPM was (whoops, gotta check the tape again, I forgot exactly)
Last edited by Masterspykiller; Nov 17, 2006 at 12:25 PM.
Safety Car
Joined: Oct 2006
Posts: 3,602
Likes: 3
From: Cincinnati OH
not sure you need a high volume oil pump. might just be adding parasitic losses (and over-scavenging the pan) under the higher RPM you'll run. hi-pressure would be a different story, but likely just a blueprinted (tight tolerance) OEM style would be perfect.
What kind of RPM do you typically pull with that setup?
EDIT: also in-spec bearing tolerances will keep those oil pressures up.
What kind of RPM do you typically pull with that setup?
EDIT: also in-spec bearing tolerances will keep those oil pressures up.
Last edited by Random84; Nov 16, 2006 at 08:31 PM.
Pro
Joined: Nov 2004
Posts: 637
Likes: 0
From: Perth Amboy N.J.
with Random 84,I use a Canton balance pump and iam over 500 rwhp.
Why guys use HP and HV pumps beats me. SBC's have never had any oil system problems,So why use them unless you have a problem.
Regards
Melting Slicks
Joined: Jun 2004
Posts: 3,253
Likes: 2
From: Castro Valley CA
A couple of questions before your final autopsy report(which hopefully will prove conclusive.) How many track hours did you have on the LT4 before failure? Was the Canton pan designed for road race use(i.e. lateral and longitudinal forces? What PN is the pan? What oil did you use? Did you run the oil level at full or over? Do you have an Accusump or oil cooler? What was your redline? When did the engine brake, during braking, turning, beginning of session, end of session? Did you have high oil consumption with the Gapless rings? Who built your motor?
Safety Car
Joined: Apr 2005
Posts: 3,624
Likes: 431
From: Dale City VA
Why were you running it "over full" on oil? Bad idea IMO for any engine. I know you may think it helps out but actually all that extra oil ends up getting slung around by the crankshaft and whipped full of air bubbles. This could be why your engine failed.
As for HV pumps, I don't use them anymore in anything (I use mostly all dry sumps now). However years prior to that I used the Melling M99 (a BB pump cut down to fit a SB cap) in alot of wet sump oval track engines without any failures, EVER. 660hp 23 degree SBC late model dirt cars 7000-7800 rpm 40-150 laps a night for an entire season before tear downs. I also used a few M55HV pumps in lower class sportsman engines, again no failures. I use oil pans made by a guy in Kansas, Larry Pankrets at Competition Componets. The finest wet sump pan you will ever see bar none, hand made, tig welded and perfect. About the same money as that mass prouduced Canton you have now.
A lot of folks have problems with HV pumps pumping all the oil to the top of the engine and then the engine is starving for oil (so I guess this why all the extra oil in the pan?), but I never have had that problem. I never used an accusump either, never had to.
All you have to do is take a die grinder to your oil returns in the block and the heads. But actually take some time and do some real grinding not this BS dremel grinding for 10 mins I see people doing. You need to enlarge the holes a lot and pay attention to where the heads and block meet. Stock almost 1/4 of that oil return in the head is blocked off by the block deck surface, make sure it isn't when your engine goes together. Also block off the little returns in the lifter valley (completely if you have a mech roller cam) partially if you have a hyd roller, to keep extra oil from getting hung up and slung around in the camshaft area. Force it go to the front and oil something that could use a little extra oil like the timing chain, front thurst sufrace of the camshaft and down the back strait to the pan where its needed the most.
Others have said this and I agree. You probally don't need a HV pump. We used to run them back in the day because we didn't know any better. They eat HP and with out proper oiling system work (ie all the grinding I explained above, blocking off the little cam returns and oil restrictors if you have a mech roller) can pump the pan dry. Melling has a new series of std volume racing specific wet sump pumps that may work well for you (PN 10552C) if it will fit in your pan. If not I would use the (PN M155).
Also proper rod brg, main brg, piston and ring clearance is very important to keeping your oil temps down and your engine life up.
With the exception of the oil pump there is nothing wrong with the parts list you have compiled. However there is a lot more to building an engine that will make HP and live than just buying expensive parts.
Will
As for HV pumps, I don't use them anymore in anything (I use mostly all dry sumps now). However years prior to that I used the Melling M99 (a BB pump cut down to fit a SB cap) in alot of wet sump oval track engines without any failures, EVER. 660hp 23 degree SBC late model dirt cars 7000-7800 rpm 40-150 laps a night for an entire season before tear downs. I also used a few M55HV pumps in lower class sportsman engines, again no failures. I use oil pans made by a guy in Kansas, Larry Pankrets at Competition Componets. The finest wet sump pan you will ever see bar none, hand made, tig welded and perfect. About the same money as that mass prouduced Canton you have now.
A lot of folks have problems with HV pumps pumping all the oil to the top of the engine and then the engine is starving for oil (so I guess this why all the extra oil in the pan?), but I never have had that problem. I never used an accusump either, never had to.
All you have to do is take a die grinder to your oil returns in the block and the heads. But actually take some time and do some real grinding not this BS dremel grinding for 10 mins I see people doing. You need to enlarge the holes a lot and pay attention to where the heads and block meet. Stock almost 1/4 of that oil return in the head is blocked off by the block deck surface, make sure it isn't when your engine goes together. Also block off the little returns in the lifter valley (completely if you have a mech roller cam) partially if you have a hyd roller, to keep extra oil from getting hung up and slung around in the camshaft area. Force it go to the front and oil something that could use a little extra oil like the timing chain, front thurst sufrace of the camshaft and down the back strait to the pan where its needed the most.
Others have said this and I agree. You probally don't need a HV pump. We used to run them back in the day because we didn't know any better. They eat HP and with out proper oiling system work (ie all the grinding I explained above, blocking off the little cam returns and oil restrictors if you have a mech roller) can pump the pan dry. Melling has a new series of std volume racing specific wet sump pumps that may work well for you (PN 10552C) if it will fit in your pan. If not I would use the (PN M155).
Also proper rod brg, main brg, piston and ring clearance is very important to keeping your oil temps down and your engine life up.
With the exception of the oil pump there is nothing wrong with the parts list you have compiled. However there is a lot more to building an engine that will make HP and live than just buying expensive parts.
Will
Safety Car
Joined: Apr 2005
Posts: 3,624
Likes: 431
From: Dale City VA
A lot of things can cause oil temps that are too high. I see it a lot in oval track engines. A number of mistakes I see most commonly from my competetors engines, is that the oil ring tension is too high (ie not using low tension rings (or piston to wall clearance is too tight) or ring gaps are just too tight and their finish hone looks like they used a brick.
Second worst/most common thing I belive is crappy oil pans. They don't keep oil off the spinning crank and when oil is all full of air it can't dissapate the temp or lubricate very well. Oiling system work on the block plays in big here too.
Also IMO rod and main clearances under .002 are just not acceptable on a race engine. Your just asking for a spun brg, I don't care what kind of oil your running. Exessive clearance is a no go too in my book. Nornally I run .0025 on the rods and mains for 50W racing dino oil and .002 for 15W50 synthetics. Rember metal parts expand when they get hot, even thou the oil may not break down, some of that clearance goes away when the journals on the crank gets that hot and the rods and it expand at different rates. In some circumstances you may get more clearance but you may get less in others. If you've only got .001-.0015 clearance your not giving much margin if something goes bad and you get a little oil temp spike. Why not give your self that cushion and it frees up a little HP running more clearance, if you have a good pan and pump the extra clearance isn't going to hurt you oil pressure. While I'm on the subject you only need 10psi per 1000 rpms. Any more is eating HP and causing more friction to turn the pump, causing more heat.
It all works together but thats the big mistakes I see others make. As far as this one blowing up, its only speculation as I can't see the parts first hand and make an actual determination. However I see 3 things that greatly contributed.
1. HV pump, and unknown oil system work.
2. High RPM engine for extended time.
3. Running it over full on oil could cause oil aireation.
IMO 275 degrees oil temp is safe, but 290 is absolutely on the edge.
Will
Second worst/most common thing I belive is crappy oil pans. They don't keep oil off the spinning crank and when oil is all full of air it can't dissapate the temp or lubricate very well. Oiling system work on the block plays in big here too.
Also IMO rod and main clearances under .002 are just not acceptable on a race engine. Your just asking for a spun brg, I don't care what kind of oil your running. Exessive clearance is a no go too in my book. Nornally I run .0025 on the rods and mains for 50W racing dino oil and .002 for 15W50 synthetics. Rember metal parts expand when they get hot, even thou the oil may not break down, some of that clearance goes away when the journals on the crank gets that hot and the rods and it expand at different rates. In some circumstances you may get more clearance but you may get less in others. If you've only got .001-.0015 clearance your not giving much margin if something goes bad and you get a little oil temp spike. Why not give your self that cushion and it frees up a little HP running more clearance, if you have a good pan and pump the extra clearance isn't going to hurt you oil pressure. While I'm on the subject you only need 10psi per 1000 rpms. Any more is eating HP and causing more friction to turn the pump, causing more heat.
It all works together but thats the big mistakes I see others make. As far as this one blowing up, its only speculation as I can't see the parts first hand and make an actual determination. However I see 3 things that greatly contributed.
1. HV pump, and unknown oil system work.
2. High RPM engine for extended time.
3. Running it over full on oil could cause oil aireation.
IMO 275 degrees oil temp is safe, but 290 is absolutely on the edge.
Will
Melting Slicks
Joined: Oct 2000
Posts: 3,426
Likes: 4
From: Heidelberg PA
Cruise-In V Veteran
Do not use a standard melling oil pump. Their engineering has changed and the are shearing off at the top of the pump. Check out
http://drr.infopop.cc/eve/forums/a/t...162#3141046162
Melling even warns you not to use them. They have new part #'s for racing pumps.
http://drr.infopop.cc/eve/forums/a/t...162#3141046162
Melling even warns you not to use them. They have new part #'s for racing pumps.
Last edited by 85vet; Nov 17, 2006 at 05:06 PM.
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Melting Slicks
Joined: Mar 2003
Posts: 2,472
Likes: 0
From: Toronto ONTARIO
Awesome info. I have been planning a rebuild of my Motor over the winter and am definitely changine the melling pump I have. Here's the question I have...
Does anyone make a STANDARD volume BILLET oil pump ?? or any un-breakable std volume oil pump for an LTx motor ??
Does anyone make a STANDARD volume BILLET oil pump ?? or any un-breakable std volume oil pump for an LTx motor ??
Drifting
Joined: Oct 2005
Posts: 1,920
Likes: 51
From: Angier nc
i would consider looking into coating the bearings,piston skirts,tops and combustion chambers on an engine that lives under this kind of abuse.
investing in a good crank scraper and a screen type windage tray might help keep any excess oil off the crank(provided the pan is'nt over filled).
investing in a good crank scraper and a screen type windage tray might help keep any excess oil off the crank(provided the pan is'nt over filled).
Safety Car
Joined: Apr 2003
Posts: 3,793
Likes: 9
From: VA
Originally Posted by Masterspykiller
We might build an identical engine, but I thought I would ask for any suggestions here, because the folks on Corvette Forum have more knowledge about C4s than anywhere else in the world.
Melting Slicks
Joined: Jun 2004
Posts: 3,253
Likes: 2
From: Castro Valley CA
Check out this oil pump setup for an LT1
http://www.karl-ellwein.org/EllweinEnginesHome.htm
Any news yet on the autopsy?
http://www.karl-ellwein.org/EllweinEnginesHome.htm
Any news yet on the autopsy?
Safety Car
Joined: May 2002
Posts: 4,010
Likes: 26
From: Somewhere nowhere
>>Car came down slight elevation change, made tight 90 degree turn right into short straight when it failed.
(specifically at Buttonwillow, CA running CW leaving Grapvine toward Club Corner and Bus Stop)<<
<<<<<<<<<<<<<<<<<<<
sounds like oil starvation.
certainly not oil temps, or anything else.
I usually run 1 qt over to prevent this.
1/2 qt over may not have been enough.
(specifically at Buttonwillow, CA running CW leaving Grapvine toward Club Corner and Bus Stop)<<
<<<<<<<<<<<<<<<<<<<
sounds like oil starvation.
certainly not oil temps, or anything else.
I usually run 1 qt over to prevent this.
1/2 qt over may not have been enough.
