GrnDragon

iTrader: (4)

I have hit the wall with this project, about to part the damn thing out. I have been trying to tune it for the last 1.5 years (that's what 3 kids will do to you).

Latest incident was doing some high RPM pulls to datalog, and when it hit the redline (6300 RPM) I saw a giant plume of smoke in the rearview mirror. Car ran and idled fine on the drive home and when I got home I saw the breather on the passenger valve cover was about to pop out and oil was spewing onto the header (I hoped that was what caused the plume of smoke). I hoped that my PCV/catch can system was just inadequate so I bought a Might Mouse catch can setup and installed it (great piece btw). I started the car it was idling fine and no smoke from the exhaust, but there was gas smelling vapor coming from the catch can. This meant that there was too much crank case pressure or not enough vacuum, I thought it was a bad PCV valve so I got some new ones and it did not fix the problem. Next was a compression test and the results are TERRIBLE.

1-145psi
2-215psi
3-220psi
4-140psi
5-210psi
6-145psi
7-90psi
8-210psi

4 bad cylinders!!!!! I have only put about 1/2 a tank of gas through the engine so it was either bad when I bought it or my one pull that hit 13 psi killed it. I would not have thought 13 psi would destroy the engine, I put a different pulley on after that pull to reduce the boost to hopefully a max of 10-12 psi. It wasn't the best engine to boost but I thought it would live fine on the street, I guess not.

Here is the info on the engine as I bought it from SDPC back in 2005.
-385 ci
-Ported & hand polished LT4 heads, Titanium retainers, SD1007 valve springs, and Manley Stainless Valves
-Block is "0" deck, 4.040 bore, clearanced for stroker crank, and 4 bolt main
-Port Matched LT4 intake
-Zero balanced rotating assembly: Callies Magnum 4340 Crank, Manley 5.7 Rods, JE Flat Top pistons, and file fit ring set
-10.4 CR
-Moroso 7 qt pan, Speed pro high volume oil pump, GM extreme duty timing set
-Manley Push Rods
-GM LT4 Hot Cam
-Engine made 485 HP @ 6300RPM/467 lbft @ 4600 naturally aspirated

I added the following
-Custom 12 rib F1A Procharger
-24x conversion
-60lb injectors
-255lph in tank with Kenne Bell BAP
-Full SS Headers and custom 4" exhaust

What changes would everyone suggest to build it the right way for a 10-12 psi F1A Procharger?

Catmaigne

iTrader: (6)

Well... you're running 13+ psi with stock compression. You should be spraying a crapload of water/meth with that kind of SCR and boost on pump gas. E85 or race fuel is another option.

Is this a 355 or 383, 396? Any idea what the ring gaps were set at? I have a feeling that stock CR means near stock ring gaps, bad for FI. I also think the LT4 hotcam is too small with more displacement and would make the DCR higher than it needs to be. That in turn makes the motor less tolerant of boost and more prone to knock.

GrnDragon

iTrader: (4)

I updated the first post, it is a 385 ci.
I have no idea on the ring gaps, but I assume they were set for running NA, since that is how it was run before I bought it.

I never meant to be higher than 10-12 psi, but guessed wrong on the pulley size and hit 13 psi once for about 1 second on one of my data logs. It must have been enough to destroy the engine????

Catmaigne

iTrader: (6)

Stock compression with that amount of boost on pump gas without any safeguards will definitely do it. No meth/water and no intercooler too? Not surprised at all. Forged pistons will "tolerate" more abuse but 5-10 psi is risky without anything to cool the intake charge or increased octane, forged or not. Other things like ring gaps and piston to bore clearance come into play and can also contribute to failure. Added heat from FI means the rings expand more and could butt if the gaps aren't wide enough. The pistons can also swell in their bores if there isn't enough clearance in the bore as well.

Do you have a wideband? The 60lb injectors and the booster pump are small, you are probably lacking fuel. 10+ psi on a F1A through that motor is a lot of power.

ACE1252

I hate to be an armchair quarterback here, but boosting an LT1 engine setup for NA applications is nothing but a ticking time bomb. I've seen it time and time again over the years on these forums with LT1s specifically not built to handle boost. More so with purely stock type engines, but it certainly sounds like you found your engine's limits.

It's an expensive lesson to learn for sure.

Time to pull it apart and see what can be salvaged.

GrnDragon

iTrader: (4)

Thanks for the info, I have done my homework on this and know the fine line I was walking. I have a large front mount intercooler, the boost was supposed to be 10-12 NOT 13 psi that was a mistake in pulley size. Even with the 13 psi it hit My lowest AFR recorded on my wideband was 10.5, yes that is pretty lean but it was for about 1 data point which is not much time at all the rest of the pull was 11-12 range. My fuel system is at about it's limit but was not the problem.

I knew I was taking a chance with running boost on this engine, but I thought since it was a built engine with quality components it could handle 10ish psi just like stock LS1's do. I have no proof that the boost actually killed this engine, it could have been bad from the day I bought it or could have gone bad when I first fired it up and the diaphragm in my fuel pressure regulator was bad and dumped a TON of raw fuel into the intake manifold and then right into the cylinders. I don't know how much damage that could have caused. So there is no way to ultimately blame the boost for killing the engine. I appreciate the info, but I am more looking for advice on a way forward on the "Proper" way to build this engine and ensure this will not happen again.

-Proper and best Rings, gaps ets?
-Best pistons for a max of 14/15psi of boost?
-With a goal of 700 RWHP what CR (9.0/9.5/10.0)?
-Best head gaskets for boost
-Should I upgrade fuel pump (350 lph in tank or dual 255's)
-New fuel lines or will stock support 700 RWHP?
-Will 60 lb/hr injectors support 700 RWHP?

RealQuick

iTrader: (14)

You are misunderstanding rich and lean.

10.5 is rich and 12.0 is lean.

you should be targeting 11.0 A/f to be safe until you get the timing where you want.

Catmaigne

iTrader: (6)

You're missing the point. Yes, there are guys running 10+ psi on stock LS1s but they're using lots of meth and/or higher octane fuels to make them live assuming stock compression. A lot of times they'll swap to heads with larger chambers, open up chambers, or use thicker head gaskets to drop compression which increases the safety margin. You're also forgetting that LS1s have lower compression and it's a totally different platform. They have less valve angle, more concentric combustion chambers, taller decks/longer rods, etc. These are small differences but still account for something.

Go over to Karl Ellwein's site and look at some of the boosted builds to get an idea of what's involved.

To answer some of your questions...
-What rings are best is totally subjective. I have Total Seals in mine with the chromium nitride coating up top. I know the Hellfire rings are also popular. I've been told to avoid rings with a plasma moly top ring because the coating can flake off with boost. As for the gaps, the manufacturer sets that spec but you usually see 0.025"+ for mild FI. I think mine are set at 0.026/0.026.
-Search 4032 vs 2618 forged pistons and make a decision. One is more for street cars and the other for race cars. 4032 gets a bad rap sometimes when design is poor, but the alloy is capable.
-MLS head gaskets without a doubt.
-Dual 255s will get you to your power goal. The stock lines will also, but they will have no headroom.
-The 60s will be too small for 700whp with normal base pressure. Go with the 80lb siemens.

Catmaigne

iTrader: (6)

If you are certain that your compression test results are correct then find out what's causing it. Could be misadjusted valves, burned valve seats, etc. If there is damage to the pistons then see if you can get some replacements. Contact JE and ask for specs on things like crown thickness and top land thickness. I think .2" would be the thinnest I'd allow and if they check out just slap the motor back together with wider ring gaps. I would also consider a cam change.

tbird31

iTrader: (22)

IMO I think the motor had something going on from day 1. There's no reason a 13psi boost spike should grenade it like that. I built a D1SC car running the same ~12psi on a STOCK bottom end and making 640whp and it runs like a champ. It's a HC motor with roughly 10.8CR with ZERO meth or water and the provided twin inter-coolers.

To answer the question of the way to build it properly, I just have 3 bits of information...

Always overbuild your fuel system. We did a Lonnie's double pumper setup with stock lines in our build. I also agree with catmaigne, I'd up the injector size.

However, I'd have to disagree with the norm of meth/water is the answer. I have always felt like it's just something else to go wrong, I like simplicity. You can build the car to make power without the use of that. This is NOT me saying it won't help, but again the car I built made 640rwhp on ProCharger optioned twin inter-coolers and mild boost. I see no reason why you couldn't get your 700hp goal with your large FMIC, the larger F1A and more boost.

Lastly, don't give up. I've been watching your car since the OG days of Tech. Always been an awesome build.

GrnDragon

iTrader: (4)

F'me! I got it backwards again!!!! So yeah the leanest it hit in that pull was low 12's. Thanks for the correction, for some reason AFR is like a double negative to me and I always don't not get it backwards.

GrnDragon

iTrader: (4)

Would anyone think that you could see that much difference in compression if the rings weren't seated yet? I would think that a 110psi difference from #7 to the other "good" ones could NOT be attributed to rings not being seated. I did put about 1-2 tsp's of oil in the #7 cylinder and it increased the compression to 125 psi, so a small change. Would that indicate rings or valves? I unfortunately don't know the full history of this engine so I don't know if it was ever broke in before I got it, but I have only put about 1/2 a tank of gas through it with only 2 hard pulls that NEVER hit full throttle but did hit the rev limiter.

Catmaigne

iTrader: (6)

Uhhhh... I wanna know more about this 10.8 SBE car. I'm guessing this is a gen3/4? Pics or it didn't happen lol

Blackbirdws6

iTrader: (7)

If the AFR was good and seems it didn't go way lean, then my only other thought is perhaps too much timing + improper ring gap coupled with stock compression and pump gas.

You can double check the valve train and make sure nothing has gone south but definitely sounds like you hurt a few holes.

I'd recommend on the rebuild dropping static compression a point, changing the cam, twin pumps, and 80lb injectors. I wouldn't run it any more at this point as you want to salvage any parts you can. Really a bummer but check with Karl Ellwein as mentioned for typical boost oriented LTX setups.

tbird31

iTrader: (22)

as to not clutter the OP thread I'll PM you.

JoeNova

The guys posting trying to compare LS combos to the OPs and using them examples as to why his 'should have worked', apples to oranges.

I run ~24 PSI on a 10:1 SBE 5.3 on pump gas.
I've tried to run 8 PSI on a SBE LT1 and it blew to pieces.

What is relevant to one doesn't always work with the other.
OP, I would run the compression check again.
Chances are, overboosting when it hasn't been tuned for it, with N/A compression and a stock ring gap did you in. How much timing are you pulling in boost?

SS RRR

iTrader: (2)

Which has always ever been the norm. Before heads and cam ATI was on the scene and multitudes of people were using I believe a 7 or 7.5(?) pulley and it would last for a bit, but lack of knowledge on tuning and those setups would grenade. For years the rule of thumb that I remember from those experienced stated to not go over 7psi on stock compression.
Back then cars were either using a 75 to 150 shot of nitrous or boost. Niether really ever had long lasting results.

GrnDragon

iTrader: (4)

Holy crap life really gets in the way of this hobby! I cannot believe it has taken me over 1 year to tear the engine apart...I finally pulled one head and found this...

Need opinions, please! The pics are of cylinders 1 and 7, which had low compression 140psi and 90psi (others had 215-220). All the cylinder walls on the drivers side have the fine vertical marks (not deep at all so I wouldn't call them scores or scratches).

The pics of the heads are also from 1 and 7, there are very small pock holes, 3 and 5 do not have them. Not sure if those are somehow playing into the low compression? Think the heads are bad? Are the holes from detonation or possibly bad casting?

I feel even more confused!?!? What is salvageable?

Puck

iTrader: (17)

Cylinder walls and tops of the pistons look fine, but there are detonation marks all over those heads. How do the plugs look?

You can't run a boosted motor to high RPM pulls, especially at ~12psi, without a SPOT on tune. Has to be tuned in stages, raising the RPM up each pull after verifying and tuning.

Having no meth and no intercooler doesn't give you much of a safety net. Do you know what the knock counts were?

Oil did not raise the compression numbers much, so it may not be the rings themselves but you could have **** out the ringlands - which would have no chance of sealing with oil like worn rigs will. Hopefully not. The next thing I would look at are your valve guides being damaged.

GrnDragon

iTrader: (4)

I do have an intercooler, and I did exactly what you are describing in slowly stepping up to a max rpm pull for proper tuning. I only ran the engine for about 1/2 a tank of gas, and only had 3-4 high RPM pulls and they were for only 2-3 seconds at a time and the data showed decent fuel on all the pulls and it never got hot. I am venturing that this damage was already done to the engine before I bought it from SDPC. It was an engine they built and raced in one of their trucks, so it was a used engine. I was told it was good and freshly rebuilt, but I never confirmed before I installed and ran it.

I guess my expensive lesson is to NEVER buy a used engine, and if you do check everything before installing.

Forgot to mention the condition of the plugs...
-First set were fuel fowled because my fuel pressure regulator diaphragm was ruined and dumped unmetered fuel through a vacuum line into the engine.
-Second set didn't show any signs of running lean or too hot, some showed what may have been oil fouling but they weren't run long enough to get much material on them.