questions for those with a 510 stroker

[JST2CRZY]

My engine builder just finished rebuilding my 96 GTS engine upgrading it to a 510 stroker. It has a rebuilt roe s/c with an 8lb pulley, water ****, reworked heads, 8.5:1 CR, roller rockers, Diamond brand light weight pistons and a blower specific cam. It currently has the stock throttle bodies but I am putting on a set of 70mm ones. My questions are:

We did an initial dyno run today and got about 550 rwhp. He said he needs to adjust the rockers more and with the 70mm TB'S I should atain approx 580 rwhp putting me a little over 700 at the crank. Does this sound correct?

Should he have used a higher CR? He stated that the lower CR will give me better reliability as well as less detonation issues. Thoughts?

 

[Red Snake]

Doesn't sound right to me.

My STOCK MOTOR 97 made 635rwhp/675rwtrq with the 8 pound pulley. Only other mods were Headers/Corsa, T&D rockers and 70mm throttle bodies.

I've since added 10 pound pulley, water/**** and Walbro 255 fuel pump to get to 660rwhp/710rwtrq.

 

[plumcrazy]

im told 9:1 is perfect for boosted applications.

 

[Sweet Ride]

We did an initial dyno run today and got about 550 rwhp. He said he needs to adjust the rockers more and with the 70mm TB'S I should atain approx 580 rwhp putting me a little over 700 at the crank. Does this sound correct?

DynoJet or Mustang dyno? Numbers sound low to me.

 

[sniper1]

510 Stroker with an S/C ? Those numbers are way too low
That set up should get numbers closer to 680 rwhp plus and 790 rwtq

 

[JST2CRZY]

Dynojet dyno

 

[Russ M]

Depends on the dyno facility. But I can assure you one thing 580rwhp does not equate to 700 at the crank, more like 640-650 crank. With your motor the blower is way too small, the roe unit isnt really big enough for a stock viper motor. Get a pair of turbos and make 900rwhp at 10psi.

 

[1BADGTS]

How conserative is the tune .

 

[1BADGTS]

How conserative is the tune .

Also is that number before or after the car is heatsoaked .On a hot day after 3 or so quick runs those things heatsoak bad.

 

[martyb]

You should be over 700rwhp with your set up, or damn close to it. How much timing, are you sure you are getting 8#'s of boost?

My car has stock bottom end, with heads, cam, and 10# on a Gen 1, and I am around 680rwhp, stock displacement.

I would say your car has ALOT left in it.

 

[Joseph Dell]

Running with a ROE, you have selected a compression ratio which is a bit lathargic. But the compression ratio only accounts for missing 3-5% of your power.

The tune could be off a bit. Temps, etc... Play a part. I would expect a motor like yours to make 620-650 at the tires.

You are also out of fuel, so that too could be part of the issue.

700+ hp or tq is not realistic. You won't see it on that car without NOS or some crack. The cylinders need a big blower to fill them and as indicated above, the head unit just can't blow that hard.

If you were going with a non-roots blower (paxton-type) then 8.5:1 is fine and you run 16 lbs of boost. For a ROE, it is a poor choice since the blower is practically overdriven in 'stock' set-up. Adding a 10lb pulley will just make the air a LOT hotter.

good luck!

 

[1TONY1]

How conserative is the tune .

Hopefully VERY conservative.

Also is that number before or after the car is heatsoaked .On a hot day after 3 or so quick runs those things heatsoak bad.

Disagree, with w/m it will keep the blower cool. With my Roe underhood temps were MUCH MUCH cooler than with turbos.

You should be over 700rwhp with your set up, or damn close to it. How much timing, are you sure you are getting 8#'s of boost?

My car has stock bottom end, with heads, cam, and 10# on a Gen 1, and I am around 680rwhp, stock displacement.

I would say your car has ALOT left in it.

I agree with Marty.
Do you know if the cam was degree'd in....as in, could it be off at the timing set. I would look for problems with the motor or tune. The compression is not your problem. With a good w/m mix you should be jacking the timing in that thing...with low compression add a little more
Stock motors with a 6.5 pulley, headers and exhaust can be in the 580's - 590's whp.

Customers car with a stroker, w/m, 10psi Roe, 93 octane:

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A.R.T. build, 9psi, heads, stock cam, 2 degrees advance timing....may not even have w/m. Not sure about the ci.
713whp, 758 tq

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[99 R/T 10]

Like all are saying, check the tune, but also 8# is minimal for the build you have. Jump it up to the 12# pulley and get somebody that can tune work on the car. Has you builder been tuning the car too? How much experience does he have with the Vec?

 

[utahviper]

Your compression ratio is low for a roe. In order for you to maximize your motor you will have to add 6-10 degrees of timing, above stock, with the 8lb pulley to get some decent power. You probably wont ever make 700rwhp unless you have nitrous. You have a good setup but too low compression for roe. This is great for paxton or turbos.

I made 720rwhp 760rwtq with a 9psi pulley heads and stock bottom end with a lot of timing. My compression ratio was stock. I agreee that the blower is too small for the motor.

Also, a good setup of heads/cam car that is 510ci can make 580-600rwhp with 10:1 compression. Your leaving alot on the table.

 

[OKViper]

My stock motored 2002 with a 5# ROE makes 550/580 at the wheels.

Yours is WAY low.

 

[Simms]

IMO, your CR is too low for an 8lb Roe setup. It is more suited for a high boosted turbo build.

As others have said, I'd go to 10-12# and upgrade your fuel system tot try and benefit the stroker build you have.

 

[JST2CRZY]

Thanks everyone for the replies so far. In reference to the heat issues, the ambient temp in the dyno room was 100 F by the 8th pull.

 

[plumcrazy]

id be careful with your fuel having those mods, you have to be on the edge......

get a real fuel system in that thing before you have a problem

 

[Red Snake]

My stock fuel system topped out at 635 rwhp.

 

[2001 GTS]

Those numbers sound really low. I did more than that on my all motor built 488.

 

[Russ M]

Anyone have a flow chart for the Roe blower? That will tell us the story of just what that unit is capable of and at what psi.

 

[Red Snake]

Anyone have a flow chart for the Roe blower? That will tell us the story of just what that unit is capable of and at what psi.

You could probably build a chart with the info posted right here in this thread (Real world results, not theory). For example:

Stock motor

5 lbs = 550/580
8 lbs = 635/675
10 lbs = 660/710

Heads/Cam

10 lbs = 680 rwhp

Stroker motor

10 lbs = 715/730

 

[plumcrazy]

get a call into greg good, he would be able to help you.

 

[Greg Good Cylinder Heads]

I just looked at your sig-line JST2CRZY.....I think the heads are junk. LOL.

But seriously, lots of guys don't do well on their first dyno session...so don't worry about it too much. I've had several Roe customers go over 700 rwhp on a Dynojet. My fastest Roe customer was too lazy to go dyno his (you know who you are )...so we'll never know what it made. I think it was near 750 though.

If there's anything I can help you with PM me. I'll do what I can.

 

[Dan Cragin]

I agree with Greg, the first dyno session is just a baseline. You spent quite a bit of time on your engine build, you need to spend some time on tuning. The key is recording your test data. Engine temp, air intake temp, boost level, air fuel ratio, etc..

When you look at power on the dyno, boost level, spark timing and air fuel are the key elements. You need to make boost (belt slip, pulley size), spark timing must be a compromise between knock threshold ( don't wont to detonate, but want to make power) and not to little timing (Low power and high EGT's). If your air fuel is too rich (10 to 1 or lower) or to lean (13 to 1 or higher) then power will suffer.

You need to work with what you have. Russ is right, that blower is small for a big motor and if you spin it too fast it will make too much heat, but you need to make sure it makes at least 8 psi. Pulley sizes do not equal a boost number, data-logging will verify this.

Be patient with your tuner, but ask questions. Let him know you are confident that he can figure it out, he has an investment in the job as well. Keep your cool.