Low compression

[olaosunt]

Finally got round to mine .
Not good .

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[robmustang201528]

Finally got round to mine .
Not good .

Looks better then mine... 6 and 8 where low on mine smh. I'm trying to stay out of boost but it's hard lol smh. My catch might have a couple of droplets in the can. Just check it this morning. What's your next step? Built motor?

 

[olaosunt]

Looks better then mine... 6 and 8 where low on mine smh. I'm trying to stay out of boost but it's hard lol smh. My catch might have a couple of droplets in the can. Just check it this morning. What's your next step? Built motor?

I suspected the motor may have been hurt sometime last year when my traps were consistently 5 mph lower than what I thought they should have been for the pulley .

I had short block built over the winter .
Second generation 5.2 voodoo bare block
Boss crank .
I am using OEM voodoo pistons that are a good quality Mahle(I got them for cheap ) . They may not be specific for DI but they have a similar dimple and my builder thinks they will work .
Rods are Manley H rods with ARP 2000 bolts .
Pretty basic build I think should be good for 1000-1100 whp.
I was going to swap my heads but decided to do a long block with new heads and valve springs upgrade .
Long block is almost ready . Just needs to be trimmed . The cam and front covers have been delayed so I may just use the ones on the stock motor .

I also scored a complete Gen 3 long block for cheap ,he will building up next with drop in Mahle pistons /H tuff rods, valve spring upgrade so I have a spare on hand .
Not sure what I am going to do with the stock long block . I thought I would have been able to sell it but probably not now since I know the bottom end is hurt .
I am considering sending it off to RPG for a sleeved stroker build that somehow got on my bucket kit .

 

[olaosunt]

And off course ARP head studs /GT500 head gaskets.
I will be switching to a 10 rib /20%OD with crank support/cobra jet plate with extra tensioner and relocating the alternator .
Probably switch later to the cobra jet inter cooler.
Kooks long tube headers to replace my cat delete
It better fly !

 

[DavidHuff]

Love the Eye Candy!
I think your mustang is going to be Bad Ass with your new build.
Make sure you use the best fuel money can buy.Just Saying

 

[olaosunt]

Thought OP may like this since he is considering an Alluminator.
It’s testament to its durability and to be honest it will do the job for most people.

 

[DavidHuff]

Is Ignite High Performance Ethanol the best fuel for these motors with the proper fuel system?
That motor showed no engine wear running Ethanol Fuel.

 

[rio16]

And off course ARP head studs /GT500 head gaskets.
I will be switching to a 10 rib /20%OD with crank support/cobra jet plate with extra tensioner and relocating the alternator .
Probably switch later to the cobra jet inter cooler.
Kooks long tube headers to replace my cat delete
It better fly !

sorry to hear about the compression test, and was this the same motor RPG built? and at least you have another motor waiting =) still waiting on mine.. sorry noob question. How can I tell the difference between a short block and long block. thanks

 

[Jackson1320]

Low compression in a cylinder doesn’t tell you why just where to look. The bottom end could be fine and it have head problems. Unless we are talking about a first gen engine 12psi is entry level and a gen 2 or 3 should have no problem with that. If it’s hurt your tune did it

 

[GreenS550]

Exactly what my '15 did with broken ring land. In my case it was a bad tune. I'm guessing the tune was wringing out max power and a few pre-detonations and bang. Like LxMike said. Looks like another was going bad.
I personally wouldn't drive the car if possible. Another problem and might hurt the cylinder heads.

 

[olaosunt]

sorry to hear about the compression test, and was this the same motor RPG built? and at least you have another motor waiting =) still waiting on mine.. sorry noob question. How can I tell the difference between a short block and long block. thanks

long block= short block plus heads (timed cams )

My compression test was done on my 2018 GT’s stock engine with 25,0000 miles . Most of it @13-15psi of boost and hiundreds of 1/4 passes . It amazing how well the car still drives . If I was not racing the car I would never have known it was down on power .

I have 2 RPG built blocks and both are good .

The first short block (minus heads ) he built with the 5.2 predator /voodoo block is in my 2015 Hellion TT car . I assembled it to a long block with the GT350 heads /Ford Racing Cana .

The second was the long block in my GT 350. He sleeved the bottom end (short block ) upgraded the rods and pistons (diamonds and Manley ).
Heads had some upgrades with springs , new seals

 

[olaosunt]

Low compression in a cylinder doesn’t tell you why just where to look. The bottom end could be fine and it have head problems. Unless we are talking about a first gen engine 12psi is entry level and a gen 2 or 3 should have no problem with that. If it’s hurt your tune did it

True . In my case I later requested a “leak down “ test to help get more information but they had already “buttoned up the car “ and would have been even more $$ to do again

Besides I already have a new long block to swap in so I may just wait till the old motor is torn down to find the cause rather have to spend another $300 on another test .

 

[rio16]

long block= short block plus heads (timed cams )

My compression test was done on my 2018 GT’s stock engine with 25,0000 miles . Most of it @13-15psi of boost and hiundreds of 1/4 passes . It amazing how well the car still drives . If I was not racing the car I would never have known it was down on power .

I have 2 RPG built blocks and both are good .

The first short block (minus heads ) he built with the 5.2 predator /voodoo block is in my 2015 Hellion TT car . I assembled it to a long block with the GT350 heads /Ford Racing Cana .

The second was the long block in my GT 350. He sleeved the bottom end (short block ) upgraded the rods and pistons (diamonds and Manley ).
Heads had some upgrades with springs , new seals

Oh wow youre prepared. And thanks for the info. I might have to call Will and see about the long block build. Should I get the 5.2 sleeved? Will said no unless im planning on making 1400 to the wheels. But i am also thinking of upgrading to the Gen 5 3.8 soon. Thanks again for all the help.

 

[robmustang201528]

Just checked the catch can after driving 3 hours....got into boost a couple times (nothing to crazy)... a small amount of oil in the can... nothing that looks abnormal. Car does feel a tad slower but it could be the heat as well... it was 90 today. Saving now for a shortblock. I was expecting more oil then that tho. Does that normal to y'all? That amount of oil in 3 hours a couple of moderate boost pulls?

 

[gimmie11s]

I suspected the motor may have been hurt sometime last year when my traps were consistently 5 mph lower than what I thought they should have been for the pulley .

I had short block built over the winter .
Second generation 5.2 voodoo bare block
Boss crank .
I am using OEM voodoo pistons that are a good quality Mahle(I got them for cheap ) . They may not be specific for DI but they have a similar dimple and my builder thinks they will work .
Rods are Manley H rods with ARP 2000 bolts .
Pretty basic build I think should be good for 1000-1100 whp.
I was going to swap my heads but decided to do a long block with new heads and valve springs upgrade .
Long block is almost ready . Just needs to be trimmed . The cam and front covers have been delayed so I may just use the ones on the stock motor .

I also scored a complete Gen 3 long block for cheap ,he will building up next with drop in Mahle pistons /H tuff rods, valve spring upgrade so I have a spare on hand .
Not sure what I am going to do with the stock long block . I thought I would have been able to sell it but probably not now since I know the bottom end is hurt .
I am considering sending it off to RPG for a sleeved stroker build that somehow got on my bucket kit .

That looks beautiful and rods/pistons look familiar LOL. I finally a got around to tearing my motor down and she's blown up GOOD lol. Number 3 piston failed and took out just about everything with it.

Looks like i have more money to spend (heads and crank).

But can anyone guess what survived unscathed?? That's right......... the dreaded, "weak junk, crappy" oil pump gears! Hahahaha... i wish the stock pistons were nearly as resilient as the OPGs...........

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