[_Marauder_]

Whats up 3si! My name is Tom and I own a 1991 VR4.

I bought the car in 2013 with 37k miles on it with a few bolt on mods.
Its at 79k right now and I believe the car has rod bearing failure.

Im having a 4 bolt block built at Merkel Racing right now and having Dave Brady at ESP in Sterling, MA put it together with a rebuilt top end.

Turbos will be 3SExecutioners and the car will be tuned on an AEM v2.
Still not sure what I'm gonna do for a clutch but this is where the build is at right now.

I would appreciate any input! Shooting for 500 reliable wheel hp and enjoying this car for many years ahead.

Lol at the busted window track and missing turn signal, this was taken during a front bumper replacement.

 

[stevecooper]

What happened to the rod bearing?
Why did it fail?

 

[_Marauder_]

Not sure how or why it failed. One theory of the cause is when my "buddy" bounced it off the rev limiter at idle for about a minute.

Cant pinpoint it though maybe blown headgasket? It was smoking for about a week while continuing to drive it until it eventually died.

But it smokes like crazy and knocks pretty good

 

[HOSS]

This would be a good time to replace 1st and 2nd gear synchros in the trans if you have not done so yet
you may want to upgrade the trans to a 25 spline hardened output shaft and vcu add a bell housing brace if you plan on doing any hard launches
all this will also require a 25 spline transfer case with a brace

 

[_Marauder_]

I was hoping the 18 spline first gen trans could handle the power, I don’t plan on launching at all.

If anything I was gonna do the upgraded output shaft and adequate clutch.

 

[stevecooper]

.

But it smokes like crazy and knocks pretty good

If it broke and you don't know why then the next one will do the same thing.

The smoke is usually broken ringlands due to too much knock which in turn is too much boost for the octane in the tank.

 

[_Marauder_]

Could that happen from putting 91 octane in it when the tune is set up for 93?

 

[stevecooper]

Could that happen from putting 91 octane in it when the tune is set up for 93?

Maybe?
It depends on the existing mods.

 

[_Marauder_]

Full bolt ons, walbro hot wired fuel pump, 750cc injectors, MAF Translator gen 1, 13Gs running 17 psi

I had just put 1,000 miles on the new clutch before it started smoking. Didnt get on it once the entire break in time for the clutch.

 

[stevecooper]

That'll do it.

 

[TurboSinceBirth]

Full bolt ons, walbro hot wired fuel pump, 750cc injectors, MAF Translator gen 1, 13Gs running 17 psi

I had just put 1,000 miles on the new clutch before it started smoking. Didnt get on it once the entire break in time for the clutch.

Those injectors are way too large for pump gas. E-85 you would have been ok but on 91-93 your injector duty cycle would be so low that the ecu would advance the ignition timing an extra 4-5 degrees over what you needed likely. You should have had 450cc injectors in there maybe 550s max and it probably would have lasted longer. I can’t see 17 psi on 750 injectors with a piggyback without knocking like crazy. Maybe 13-14. At least with AEM you’ll solve some of those issues and hopefully whoever tunes it will setup some failsafes. 500whp is easy to get there reliably even on a stock 2G bottom end. I’ve made over 600whp without touching the motor but the tune has to be spot on all the time no room for error and you have to be monitoring it constantly knowing what you’re looking for unless you have a stand-alone to do that for you with failsafes setup.

 

[_Marauder_]

So basically putting 91 in didn’t help the situation but either way the combination of injectors being too big with a piggy back and too much boost is the reason why it failed.

 

[TurboSinceBirth]

So basically putting 91 in didn’t help the situation but either way the combination of injectors being too big with a piggy back and too much boost is the reason why it failed.

If you would have had a datalog with rpm, boost, ignition timing, and ecu load I could have shown you exactly where you fell at on the stock ignition map we have available because of chrome and pretty much guaranteed you would have been in the middle of it vs the far right side. It also sounds like you were never monitoring knock and wouldn’t have known any better if the engine was.

If you want a good read on why it failed, then take a look at Trevor’s thread: Tech: My take on injectors vs. timing control vs. HP.... It will explain why you had lower injector duty cycle and higher ignition timing as a result. Remember that a piggyback is just modifying the airflow signal and shrinking it or expanding it for less or more fuel. It is not injector control directly like a flashed ecu or standalone EMS.

 

[_Marauder_]

I ran the car with that setup for about 3 years I’m surprised it lasted that long. I was told the larger injectors and extra fuel would act as a fail safe for my setup.

I am definitely gonna data log from day one once I’m back on the road with the AEM

 

[TurboSinceBirth]

I ran the car with that setup for about 3 years I’m surprised it lasted that long. I was told the larger injectors and extra fuel would act as a fail safe for my setup.

I am definitely gonna data log from day one once I’m back on the road with the AEM

Well, I hope you get a better tuner this time that knows these cars a little better and also how to setup failsafes in AEM. If they do it right, you won't ever have to datalog. The ecu itself will cut fuel, boost, timing, etc. when there are problems and you will know something is wrong because it's a night/day difference in how it runs. Unfortunately, not every certified AEM tuner will set those things up on a complete tune because they don't want to put in the time for it usually because they're not getting paid for it in their standard price.

 

[jrhorne]

Those injectors are way too large for pump gas. E-85 you would have been ok but on 91-93 your injector duty cycle would be so low that the ecu would advance the ignition timing an extra 4-5 degrees over what you needed likely. You should have had 450cc injectors in there maybe 550s max and it probably would have lasted longer. I can’t see 17 psi on 750 injectors with a piggyback without knocking like crazy. Maybe 13-14. At least with AEM you’ll solve some of those issues and hopefully whoever tunes it will setup some failsafes. 500whp is easy to get there reliably even on a stock 2G bottom end. I’ve made over 600whp without touching the motor but the tune has to be spot on all the time no room for error and you have to be monitoring it constantly knowing what you’re looking for unless you have a stand-alone to do that for you with failsafes setup.

+1 for this.

I would highly recommend going E85 with those injectors, assuming you have it available. It will make your power goals much safer and easier to achieve.

 

[_Marauder_]

Should I try to contact Pampena? Or anyone else in the New England area you guys trust?

 

[TurboSinceBirth]

Should I try to contact Pampena? Or anyone else in the New England area you guys trust?

Ray is the only one in the northeast I would trust to tune an AEM 3S. Talk to Dave and Ray about your mod list and goals as well.

 

[_Marauder_]

Little update

Just got off the phone with Merkel, they said the 4 bolt block they were going use is no good!

So now I am on the hunt for a good block for them to use.

 

[Vince_Cuts_Vinyl]

What's up marauder, I'm Vince, I have a Mercury Marauder and 91 VR4

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