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Ran my brand new RHS block 435ci engine in on an engine dyno, including calibrating the Motec ECU to suit, after several hours of tuning the engine produced 685BHP at 7,000 RPM and 554 Ftlb's of torque at 6,000RPM the engine ran faultlessly.
We installed it in the chassis, see attached photo, and after some running we noticed vapour coming from the catch tank, we did 3 installation laps out on the circuit, and then checked systems, fluid levels etc, and discovered very creamy coloured engine oil in the reservoir, with typical scum under the cap etc.
The engine is normally aspirated, and we used a .040" Cometic head gasket on the 4.165" bore of the RHS block, and the new LSX cylinder heads with the extra bolts etc. We have not taken the engine out of the car yet but we do know from the data that all the pressures and temperatures of the water system were all well in spec, so there is no possibility that any combustion pressure has spiked the water pressure which rules out a blown head gasket.
Logically the only way water can get into the oil is by a gasket leak, or up through a head bolt.
Does any body have any experience with Cometic head gaskets not sealing properly on large bore RHS engine blocks?
Ran my brand new RHS block 435ci engine in on an engine dyno, including calibrating the Motec ECU to suit, after several hours of tuning the engine produced 685BHP at 7,000 RPM and 554 Ftlb's of torque at 6,000RPM the engine ran faultlessly.
We installed it in the chassis, see attached photo, and after some running we noticed vapour coming from the catch tank, we did 3 installation laps out on the circuit, and then checked systems, fluid levels etc, and discovered very creamy coloured engine oil in the reservoir, with typical scum under the cap etc.
The engine is normally aspirated, and we used a .040" Cometic head gasket on the 4.165" bore of the RHS block, and the new LSX cylinder heads with the extra bolts etc. We have not taken the engine out of the car yet but we do know from the data that all the pressures and temperatures of the water system were all well in spec, so there is no possibility that any combustion pressure has spiked the water pressure which rules out a blown head gasket.
Logically the only way water can get into the oil is by a gasket leak, or up through a head bolt.
Does any body have any experience with Cometic head gaskets not sealing properly on large bore RHS engine blocks?
Wow that sucks man, especially that its new. The only way a head gaskets leaks is through over heating or not installed correctly, sealer on the bolts or studs,torque sequence, etc,. As mentioned, maybe cracks in the block. Hopefully you find the culprit.GL
They are know for cracking even brand new, most were boosted guys but some nitrous guys cracked them also. Think it was around head bolt holes. OP you can search RHS LS block cracking and you will find some. Hopfully not your problem.
The Dart block maybe a good choice as STEVE @ RED designed that block adds up to. It may be the best as he's the Resleeve King.
Nothing beats the factory 80% of the time.
Call Comp Cams or RHS and ask for a Manager and get a.... REFUND . Don't let him off the phone with out sending you a new block or your money back.Real talk brother. Cuz, I don't believe they would want to see a as Ignorant person as me @ there doorstep about my $ talkin 4800 U. S. American Dollars.
Man I tell ya..... it's a shame that a aftermarket company would release a product that cost a large amount of money and they have problems like this then they do nothing at the faculty to try to address the issue.
Really is devastating.
Man I tell ya..... it's a shame that a aftermarket company would release a product that cost a large amount of money and they have problems like this then they do nothing at the faculty to try to address the issue.
Really is devastating.
Hi Tusky and all who have read and commented on my post,
I just need to clarify one point, my RHS block is the cars original engine block, and never gave a problem with many hours of hard out racing. I had the engine rebuilt with new LSX heads and a cam from Kip, etc and had it bored to 4.165" [from 4.130" which RHS states the block can be safely bored to] and assembled by my regular engine builder.
Logically, I don t believe the bore can not be cracked because you would see a rapid increase in water pressure, and as we log evert thing in the MOTEC ECU we can see that the water pressure and temperature is absolutely stable. So until we strip the engine down, next Tuesday, we wont know the real reason water ended up in the oil, my pick is the head gasket between the bore's is not sealing effectively.
As we never had a problem on the engine dyno I am picking the gasket is probably doing the job when there is no water pressure, but when the engine is in the car obviously it is going to build pressure.
I am also thinking that we might have created our own problem, by pressure testing [30 psi] the whole cooling system when the engine was dead cold and at around 10º C [50º F]
Finally, I have heard that some Ls engine racers leave the pressure cap of the system until the engine has warmed up, and that sounds like a good start up practice because we know that alloy block's and head's expand significantly when they are at operating temperature [80ºC]
Thanks to all of you have posted helpful thoughts on this thread, its most appreciated.
Hi Tusky and all who have read and commented on my post,
I just need to clarify one point, my RHS block is the cars original engine block, and never gave a problem with many hours of hard out racing. I had the engine rebuilt with new LSX heads and a cam from Kip, etc and had it bored to 4.165" [from 4.130" which RHS states the block can be safely bored to] and assembled by my regular engine builder.
Logically, I don t believe the bore can not be cracked because you would see a rapid increase in water pressure, and as we log evert thing in the MOTEC ECU we can see that the water pressure and temperature is absolutely stable. So until we strip the engine down, next Tuesday, we wont know the real reason water ended up in the oil, my pick is the head gasket between the bore's is not sealing effectively.
As we never had a problem on the engine dyno I am picking the gasket is probably doing the job when there is no water pressure, but when the engine is in the car obviously it is going to build pressure.
I am also thinking that we might have created our own problem, by pressure testing [30 psi] the whole cooling system when the engine was dead cold and at around 10º C [50º F]
Finally, I have heard that some Ls engine racers leave the pressure cap of the system until the engine has warmed up, and that sounds like a good start up practice because we know that alloy block's and head's expand significantly when they are at operating temperature [80ºC]
Thanks to all of you have posted helpful thoughts on this thread, its most appreciated.
Cheers,
Mark.
I thought this picture of the my Mosler MT900R- GT3 car that the engine is fitted to might be of interest to some.
For those of you that have followed my "big bore short stroke 400Ci thread on this forum, this is also the car that that engine will be fitted to once we have further developed the car.
Anything could of of happened to block when it was out eg dropped, head bolt pulled a thread and cracked etc etc. Very hard to rule out crack with a block that others have had issues with. Find it difficult to think had gasket on 6 bolt would blow through on n/a motor. I hope for your sake it is though
I thought this picture of the my Mosler MT900R- GT3 car that the engine is fitted to might be of interest to some.
For those of you that have followed my "big bore short stroke 400Ci thread on this forum, this is also the car that that engine will be fitted to once we have further developed the car.
Sorry about your troubles with this engine. Been following your other build and excited to see the results. Can't even imagine what it's like in that car!
Camster
Could you elaborate on your recommendation for not going below
.053 head gasket thickness for large bore. I was planning .040
Gasket with my 4.175 Bore 11.75:1 Comp Build. Also did you
Mean piston hitting the head vs heating the head?
Kiwi
Regarding pressure testing with 30 Psi and 50F temp
Would this perhaps be another benefit to circulating and
Preheating Coolant (as well as oil) on these very High
Investment Engines?
I am curious about the same thing, that 0.053" recommended thickness... Not that I know a ton about LS engines, but I haven't seen that before. I can guess that the thinking is that you need the thickness to make up for the thin distance between the bores, but I'd like to learn more.
Camster
Could you elaborate on your recommendation for not going below
.053 head gasket thickness for large bore. I was planning .040
Gasket with my 4.175 Bore 11.75:1 Comp Build. Also did you
Mean piston hitting the head vs heating the head?
Kiwi
Regarding pressure testing with 30 Psi and 50F temp
Would this perhaps be another benefit to circulating and
Preheating Coolant (as well as oil) on these very High
Investment Engines?
Hi NB,
We have an oil heating blanket on the dry sump tank, and I recently ordered a New Zealand made water heating circulator, as I believe that bringing the block up to temperature before you start a race engine is a good thing, so yes I agree with you, all good practice's, and in particular leaving the pressure cap backed off while circulating the water, also seems like a logical thing to do.
Steve@RED, told me the that the LS blocks grow as much as .012" which equals a lot more squash on the gasket, so using that sort of growth before you start the engine has to be a good thing.
Camster, I would and will be extremely surprised if the pistons are hitting the head surface, we run .036" squish, with a flat top piston, but thanks for your suggestion we will definitely check this if we do decide to pull the head's off, but first we will run some Moroso Ceramic engine sealer through the engine, as per Steve@RED suggestion.
05-30-2015, 03:58 AM
Help, water in the oil of my new RHS 435ci build 
