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Discussion Starter #1
Details: 2005 Mustang GT
On3 / MP 70T .68 A/R
5 Speed /Spec 2 Clutch
3:55 Posi Rear
GT500 Pumps with upgraded power wire

Bought this car last winter and it was a beast. At 15# of boost it was very quick although it seemed to fall off of a little at the top of the power band. Some of you know this car as KrisR owned it before me. It had put down 700ft/tq and 600+ RWHP on E85 in the past. Anyhow this summer it started to smoke a little and thought I had a PVC issue or at worst a turbo seal going. Not that lucky did a compression check and a few cylinders we low so the motor is out with suspected ring issues. As it sits now hoping to send it out to MMR for a freshing but thinking about upgrades while out. And would like the experts opinion as I come from a LS/BB GM background.

1. Compression- At 8.5 right now it was kind of weak out of boost. I see the new Cobra Jet is running 9.5 with turbos, with 93 octane could I get away with increasing my compression and maybe my turbo will carry upper RPMS better as it shouldn't have to work as hard to overcome lower compression?

2. Heads & Cams- Plan on using upgraded valve springs regardless and having the heads reworked. On a street with occasional strip use is cost to upgrade cams or have heads ported worth it. Maybe considered sending engine out as a longblock for MMR to do cam and head porting.

3. MMR 2500 series pistons and Stainless Steel or Hellfire rings- Do not want to have to pull this again. Figure using the best parts I can get my hands on. Opnions?

4. Headers- Shortys do not look like they would be much better than stock manifolds. Thinking of wrapping manifolds or would that make them crack?

5. Head studs or factoty bolts. I have yet to read anyone mention a failure because of the head lifting in fact I believe this car has stock bolts and has pushed pretty good power?
MMR seems to have reasonable prices but are their any other shops or individuals that do Mod Motors in the Cenral Illinois area. I have built a few motors in the past but really just do not have the time or location to do the rebuild. The longblock is out of the car and would be willing to trust someone else to do the work?
Thanx for you opinions/suggestion!

2,043 Posts
On compression, stock 9.5:1 is safe and reliable as long as it's tuned by a true day in, day out 3 valve pro. You will pick up power across the board.

Stage 2 cams/springs will be very streetable and will wake up the upper band like mad. I went from a Procharger which screams up high to a Whipple and missed the upper pull. After doing a stroker shortblock and stage 2 cams/springs and mild exhaust porting the upper band feels as strong as ever.

Running high or any boost for that matter will benefit from high quality components, period.

I doubt the manifolds would crack, but who knows. I'm all for longtubes. Ceramic coated.

Anything over 10 psi seems to merit ARP studs as far as the heads are concerned. I did it and I sleep better.

As far as who to do the work...a lot of guys do not like MMR, I wouldn't know as I've never had first hand experience with them. My first choice would be RGR. Contact JPC Racing and they will hook you up with the number. Another would be JDM engineering. That's where I bought my shortblock and it's been trouble free for about 15 months. RGR will be higher priced I believe, but Rich Groh goes that extra mile and his blocks and heads are as good as it gets.
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