siggyfreud

Even at 10 you SHOULD be able to run 5-7 psi. An honest answer will depend on more details such as the cam profile and cylinder head design/materials. But generally, 10:1 is good for more than 2-3 psi. But if you're going blown, stick with the 9.3-9.4 instead of adding additional cost to do something custom. You WILL make more power on 5 psi running at a static 10:1 than 9.3:1, but you can potentially run more boost on the 9.3:1, making more power overall.

Blue10

DSS Racing offers the kind of short block I'm looking at with -16cc dish pistons, making a CR of 10.14 with the stock 51cc heads.

http://www.dssracing.com/ProductDeta...M&Show=ExtInfo

I would keep the stock cams, etc. The only engine mods would be this shortblock, the Roush M90 kit (http://http://store.roushperformance...l.aspx?ID=1185), and a new tune.

siggyfreud

Your Roush link doens't work. Is it an intercooled setup? If so, I think you'd be good for 4-5 lbs of boost.

However, if I were you and I was spending that type of money on a short block, I'd go with the -25cc pistons and run more boost. That extra bore/stroke is going to give you the off-idle power you'll lose with lower compression. Plus, outside of boost you'll gain more economy .

My stroker gets better MPG than the stock 4.6 did (outside of boost of course).

Either way you'll end up with something fun. But I'd be hesitant to spend 6k on a motor and only be able to run the same amount of boost as a stock 4.6l.

Blue10

Sorry for the broken link...trying again...

http://store.roushperformance.com/detail.aspx?ID=1185

It has the same intercooler, etc. as the TVS R2300.
I'm "resource constrained" (on a budget), so a new short block AND supercharger upgrade isn't likely.

I'm also very "reliability conscious"...so replacing the powdered metal internals with a forged shortblock is the higher priority (insurance against detonation over the next 10 years I plan to drive this car).

If I can get a forged short block, add some low RPM performance (more fun for daily drive), and increase the "cool factor" with more displacement (five-point-THREE), that's a "win".

But if I'm going to make the car less fun to drive or cause any reliability issues, that's a "fail"...might as well just swap in an Aluminator 4.6L forged short block with the stock CR for less $$$, keep the same performance, and call it a day.

Blue10

I would expect at least 540 HP at the flywheel with the TVS upgrade alone, maybe 50 HP more than that with the TVS AND the 5.3L/323cid short block.

Based on what I've seen here and elsewhere, I would start worrying about long-term (10-year) reliability of stock transmission, etc. at anything above 500 HP...and upgrading more stuff like that would be additional cost that I don't want.

With the budget constraints I have, I would rather stick with the kind of peak HP at high RPM that I already have and focus on gains at lower RPM.

So does it sound right that the M90 boost would drop from 5psi to 2-3psi changing the short block from 4.6L & CR=9.8 to 5.3L & CR=10.14...or is that only going to happen if I drop the CR below the stock 9.8:1?

And thanks again, siggyfreud, for taking the time to think about all this and to reply! I know my objectives are quite different from what most folks are trying to accomplish with their modifications, so it's a big help to get feedback from folks with actual experience (not just theory).

Anyone else have similar/different opinions?

BruceH

You could get a 5.3 built with an iron block for about $2500 less than the aluminum shortblock you are looking at. Another option would be to build it yourself. IIRC the big bore pistons are less money than standard 3.552" 4.6 pistons. Another idea would be to skip the stroking and stay at 5.0 with 3.700" pistons and stock 3.554" stroke. It would keep the costs down a little and really be unique.

Blue10

There are several body parts I would give up if I could trade them for the skill to build it myself! But unfortunately I can't, and I don't know of anyone in my area that I would trust to do it either.

I seriously considered the iron block to save money, but couldn't bring myself to add another 100 pounds to the front of the car.

Simon1

Use the money you save to replace some items to take weight off.

Blue10

What would $2500 replace that would remove 100 pounds from the front?

Relocating the battery to the trunk is on my "to do" list, but it's not that heavy.

BruceH

K member, balancer, clutch, pp, flywheel, and exhaust manifolds would be a good start. An aluminum drive shaft would help too. I don't think it's going to be a total of 100 pounds. FRPP lists the weight at 160. A stock 4.6 is over 80. On a side note I think I have at least 50 lbs of dynomat in my car.

I just remembered something about the aluminum big bore block. There were problems with the liners leaking because of bonding and thickness. Might want to research that some.