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Went to the Dyno today. NOT GOOD RESULTS. DYNO sheet added

2.4K views 43 replies 23 participants last post by  MPE Racing  
#1 ·
I will post Dyno sheet and Dyno video later.

First pull make sure everything was ok. 250RWHP.
Second full pull things were still ok. 300 RWHP.
S/C belt needed tighting small coolant leak from around inlet of radiator.
Third full pull now this is when it when BAD. 5500 RPM. 356.29RWHP and 333.01 RWTQ

At 5500RPM steam started filling up the engine bay from the front of the motor? I was videotaping so I am not sure the location it was coming from. Dez stopped the run as soon a he seen the steam cloud. Looked at the Engine bay could not see anything leaking. Coolant all over the place. Let the engine cool down, resarted it everything was ok, shut it down. Restarted it again same steam looking gas coming from drivers pipes. Dez says head gasket. Was able to drive the 10 mile ride home. Any idea how the coolant leek occured? Drove the car home with no problem, no leak? Is it possible for something to leak at full pressure and not under normal drving. I am going to perform a pressure test on the coolant system. Also going to pull the plugs.

John

[ February 21, 2007, 07:18 PM: Message edited by: Cobra 302 ]
 
#3 ·
Sounded like you had a good pull going when it decided to hemorage. Sorry to hear.

I just got home from my dyno as well today. I'm updating my post right now with the results.

Sorry to hear about the head gasket. :(
 
#4 ·
My 302 does the same thing. Coolant comes from overflow tank because exhaust gas leaking into coolant. I did a leak down test after removing thermostat and filling goose neck to full. The number 3 cylinder was leaking air into coolant because it was bubbling from goose neck. The head gasket has a leak, when you push RPM.

Frank
 
#5 ·
Yes, it is possible. My car did the same, while not boosted.

The coolant system would pressurize the instant I would put my foot in it, and coolant would spew out around the fill cap and overflow can. It was the driver's side head gasket. While driving responsibly, no coolant issues whatsoever.

From what I've been reading, blowers are hell on head gaskets. Did you have new head bolts and gaskets when you put your blower on, or are the bolts/gaskets well worn?
 
#6 ·
I never pulled the heads off.
This motor was from the donor.
It was rebuilt not that long ago from a local speed shop. I am pulling the plugs tonight and see what I find.

Would a coolant pressure tester find the issue, or wous this happen only under boost?

I don't want to pull the heads unless I am sure that is the proble.

John
 
#7 ·
Sorry to hear about your misfortune. I have been following your posts as of late seeing as though I just installed a KB blower on my car. I am planning to take it to the dyno when the weather is better.

Where did you have the runs done? I don't know the name Dez, but I was planning on making the trip down to MPE racing.

I took the car out today for the second time since the install. Have only gotten on it a couple of short runs and so far so good, but I too am dreading the head gasket blowing.

Good luck.
 
#8 ·
Pressure tester and compression test likely won't reveal anything; it didn't in my case.

My problem was that I reused the stock head bolts when I rebuilt my donor motor. I used a very expensive Fel-Pro head gasket, too. But the stock head bolts are a one-time use. When I put the engine back together and torqued the head bolts to spec, they actually weren't tight enough, and the heads would effectively lift off the block under high-RPM (high pressure) situations, and allow pressure into the water passages, thus pressurizing the coolant system and spewing green goo everywhere.

Using a blower amplifies that problem even more, as you are only adding more pressure in the cylinders to lift the heads.

I'd suggest new head bolts and good head gaskets. No other way around it. I farted around with my coolant issue for literally months until I bit the bullet and did the teardown. Sure enough, blown head gasket.

The Fel-Pro gaskets I used are the 1011-2; they are a bit cheaper in the latest Summit catalog compared to what they used to be: $31.99 each.

If you are going to keep a blower in your car, you should probably do the right thing, and get really good head gaskets.

For what it's worth, I looked into putting a blower on my donor motor, and after talking to lots of folks on this forum and in other places, precious few of them have never replaced head gaskets. Seems the low boost blowers (5-6PSI) can sometimes keep out of trouble, but anything above than on a donor motor and it's head gasket time.

There's a local Cobra owner with a fairly high-boost blower that's changed out head gaskets upwards of a half-dozen times.

Bad news, but once you get after it, it's a pretty easy task to change the head gaskets. It took me 2 hours to teardown and 2.5 hours to rebuild. Don't forget all new upper and lower intake gaskets, too.

Sorry, man. I feel for you.
 
#9 ·
Dez is in front of seekonk speedway.
I know alot of guys who have used him.
I am not taking anything away from anyone else.
Another reson is that he is close to me. So I was able to drive it home.

John
 
#10 ·
Thanks for the advice. It really sucked seing all that coolant/steem on the last run. I don't have a problem changing the head gaskets. It's reinstalling the valvetrain that has me uneasy. What I think I am going to do is get it appart and have Dez reinstall just the heads and valve train. I will finish the top end.

I have the receipt for the motor and the bolts were ARP, and they had new gaskets? I will buy a really nice set so I don't have to deal with this again.

Another question what what are the chances the head bolts backed off from the heating/ colling cycle? I had this probelm the the intake.

John
 
#11 ·
John.

When you have the heads off check them for flatness as well as the decks of the block. Ford and TFS are often off by enough that it can cause a problem. Being slightly out of flat may be OK for a stock NA motor but not for a blower motor.

Were you watching the A/F ratio during the dyno pull? Or fuel pressure? Going lean on a blower motor under load will kill head gaskets in a real hurry.
 
#12 ·
Also, the lower intake could've been overtorqued, thus lifting the heads.

I wouldn't sweat reinstallation of the valve train; all you are doing is dropping in the pushrods and torqueing down the rockers; not a tough task.

For the lower intake, you have to go 'round the whole intake literally 6 or 7 times to get them torqued right.
 
#13 ·
THe intake was loose. I retorqued it to spec.
Isn't there a procedure for installing the rockers? I am going to have the heads inspected before I reinstall. What is the best way to check the block? It is staying in the car.

JOhn
 
#17 ·
You need O-ringed head gaskets and good head bolts to play around with more than 8 lbs of boost and a Vortech. Sorry if someone else already said this I didn't read alll posts. A donor motor with no prep work will puke out all kinds of parts with a serious blower on it. The good news is that ...once the block and heads are prepped properly....changing head gaskets will be a thing of the past. I has a stock 351 block O-ringed with TFS heads and I ran a Paxton NOVI at 25 pounds of boost....no problem.
 
#18 ·
I blew a head gasket last summer in my lightning. 351 with a vortech s-trim and about 10 # of boost. took a piston with it. I rebuilt and added Kometic head gaskets and ARP studs. Shuld cure the gasket problem. My 4.6 DOHC cobra motor came factory with the Kometic style gaskets as well. They are full metal layered gaskets. Work very well under pressure and are probably available thru summit though I get them from a local shop.

Im scheduling Dyno time now for the final tune in and to find out what its making, it sure was a change from the stock lightning setup!
 
#20 ·
Did you get dyno plots with AFR?

Detonation is the typical cause for popping head gaskets. 3 things to watch fuel, timing, inlet temps.

Detonation pressure far exceeds anything your blower can ever add.

I'll agree with Wade, replacing head gaskets is a good thing, considering the other options. The Cometics and other MLS gaskets require a smoother finish on the head and block deck or they like to leak oil.
 
#21 ·
Ok I uploaded the dyno sheet with the A/F ratio.
Pulled the plugs from the drivers side. The plug from number seven was wet. I don't know if you can tell from the picture.

John
Left plug was wet


Image



Image
 
#23 ·
John the valve train shouldnt give you any trouble at all. In fact I think you can get away without totally removing the rockers. just loosen them all the way then roatate them out of the way and pull the push rods out. Now you wont lose there location. push rods should be put back in ther proper loaction, but I am willing to bet it will make no difference. I never labeled mine. thats it for the valve train. Once the heads are reassembled just tighten the rockers to the proper tourque. No adjusting needed. If you need a hand I am here for ya
Mike
 
#24 ·
I would plan on popping off the heads, take a look at the pistons to determine if they are cast or forged, use ARP head-bolts (minimally) or Studs preferrably, and the best head-gaskets out there.

Putting a wheezer on an engine makes them work extra hard.

If you have cast pistons, make sure you are running a boost timing controller or really limit the amount of total advance.

Always remember this;

The Ford 302 needs very little excuse to blow a headgasket even normally aspirated. They have only 4 7/16" headbolts to hold everything together whereas everybody else has 1/2" bolts or 5 or more headbolts per cylinder.

This is and always has been my largest beef with Ford's engineering. Next up is the sorry cam/distributor drive gear interface but I'll save that whine for another thread..
 
#25 ·
Mike not only are you a great vendor but a great person. I will keep your offer in mind. I will pull everything appart this weekend if I have time. Now I need to find a good head gasket. I am looking around for a good quality gasket. I don't want to do this again.

John
 
#26 ·
um, yeah. welcome to the world of superchargers.

1) as others have stated, the stock head bolts are "torque-to-yeild" and are single use only. If your going to keep the SC at the boost level you've listed in your signature, upgrade to 1/2 ARP studs.

2) o-ringed head gaskets are great, but not all that practical for other then race engines. A good set of FelPro or FMS designed for a SC will work - they are typically a three composite gasket. If someone mentions solid brass gaskets - kick em in the shines and walk away. You WANT the head gasket to blow - not crack the head or break a piston.

3) torquing down the heads should be done in a five step process over a period of 24 hours. Do the first two rounds; up to about 50 lbs. Let it sit for a few hours. Repeat cycle up to 80% of final. Let it sit overnight. Do the final torque cycle. The head gaskets compress over time. This is the only approach that will achieve the correct final torque spec.

4) I see you have 42lb injectors - good. But how is the rest of the fuel delivery system? You should have at least a 255lph in-tank and T-Rex / boostapump. However, this setup is prone to creating a fuel starvation situation (due to cavatation after long steady higher RPM driving and then nailing it). A better option is a single external fuel pump ouside of the tank with 1/2 line running up to the engine bay. The stock fuel rails are good to about 450 hp. Make sure everything has been calibrated correctly for the injectors. Not too mention, check the fuel pressure regulator and ensure it's not set for too high a fuel pressure.

5) You should have an MSD or Vortech branded MSD box. This is okay, but you really need a boost retard capability if your running over 9lbs of boost. With this it will automatically pull timing off as RPM goes up - this avoids detenation - which causes head gasket / head failure. Check this and your distributor timing.

6) fuel octane with more then 9lbs of boost should be no lower then 92 - especially if your doing a dyno run. If you run lower then 92 octane, don't run it up over 4 grand. If you are really running that much boost with aftermarket heads, 92 with an octane booster should have been used for a dyno run. Anyone with real SC experience can tell you this one.

7) replace both head gaskets. You can find out which one is leaking now, but the next time you get close to red line you'll have the opprotunity to change the other one.

8) anytime a head gasket blows, have the heads checked for cracks and then have them surfaced. Sometimes the head can be fixed if it is cracked - if your lucky. Always have the heads surfaced when you change head gaskets; this ensures the best possible seal. Dont have the heads shaved for more compression though - unless you're really ready to committ to frustration of a race motor.

9) check the belt tension. You dont want it too tight, but if its loose it can actually cause more problems as the boost level with fluctuate significantly as it slipps and grabs. Race cars use a cogged belt to ensure a) no slippage and lose of HP and b) consistent and predictable boost build up.

10) Bars Leak or Prestone radiator fixer. Put one in the trunk. This gunk gets poured into the radiator and helps seal up minor gasket leaks. Might be enough to get you home sometime. I know some folks who put a bottle in after changing the head gaskets (and a few miles of shakedown) as a minor preventative. I have not done that, but I have used it on several occassions to get my sorry butt home. NEVER run the car hot to get it home because your running out of coolant - unless of course you want to crack a head for sure.

11) keep an eye on the thermostate after you change the head gaskets. Sometimes it will get clogged with head gasket junk and fail to open. While your at it; you should be running a 160 degress theromostat. Heat causes the motor to detenate more quickly; regardless of octane level.

12) your motor - as the miles go up the boost must come down or the timing retard gets bigger or the octane goes up. The rings wear and let a film of oil past under pressure; this decreases the effective octane level in the cylinder and leads to quicker detonation.

From what do I speak - 10 years running a Vortech supercharged Mustang, 100,000 15lb 550hp supercharged miles. Multiple head gasket changes, four sets of new heads to replace cracked ones, working with local Mustand speed shops, access to Ford SVO engineers through work....