I'm building a 355 now with SRP forgings, Eagle h-beams, arp main and head bolts, ported lt4's with a 224/236 -114 lsa comp cam, ~12 psi of boost from the D1SC...im curious as to what kind of numbers you guys are getting with boost out of 355's. Post dyno numbers and modifications!

 

I've seen enough dyno numbers to know you should be in the low to mid 500 rwhp area.

 

Well i would hope for at least 550 rwhp considering it put down 446 to the tires with cyl 5 showing 50% on the leak down test. Since then, ive taken the mid length headers off and added the following:

~Pacesetter long tubes with lanes true duals
~SRP forged pistons
~Eagle H beam rods
~MSD vented opti with 8.5 mm wires
~224/236-114 lsa .535 intake .555 exh with crane 1.6 rockers
~ported LT4 heads 2.02 int 1.60 exh
~12 psi boost
~dyno tuning next week when the short block is finished

What should this combo be worth? Also what kind of numbers are you other 355 guys putting down?

 

You may make more. I didn't notice that your 446 rwhp was basically on a stock motor ...considering you didn't have full compression on one cylinder that is very good. For comparison's sake, on a very conservative tune I made 384 rwhp with the Powerdyne hitting 7 PSI, long tubes, 1.6 RR's, Borla catback....othewise pretty much stock. Considering you pushed only 1 PSI more and had intercooling and true duals ....62 rwhp more than mine is pretty darn impressive. Of course, to get to 8 PSI through twin intercoolers means your impellor was spinning a lot faster and the cool air is a big help I would think. Mine could have made 400 with a more aggressive tune but I just didn't want it that way.

Now that you've got long tube headers, better heads, better cam, etc ....you may make over 550 if you pulley up some to keep the PSI at 12. If you leave the same pulley on you're likely to drop to 9 or so with those changes and maybe get to 510 rwhp or so.

Just an opinion based on observation, ya never know, you could have a freak of sorts depending on how well the heads are ported.

FWIW with my current combination the PD is again hitting about 7 PSI (has been pullied up some more) and it can max the MAF out at 471 GPS ...usually that's about 1:1 with RWHP but I'm not sure I'm buying the idea that this PD is making that much.

 

yea i was really impressed with the numbers provided i did have a bad cyl and the F/A ratio went up to 15:1 at 5500!!!

But we fixed the fuel problem with 30 lb injectors, a ross FMU, vortech inline pump and a 255 walbro in tank..any plans to upgrade the PD?

 

PD is pretty much upgraded to the max without major changes. There is some relatively new upgrade kit that allows you to go up quite a bit but I still think the lack of efficiency and low cfm wouldn't make it worthwhile, plus, it's not so cheap as the whole thing's pretty much gutted and redone. I'd rather switch to a V1 or V2 S-Trim and use an Aftercooler with upgraded tank and pump, from what I've read that's the type of cooling system I would prefer for my uses. The S-Trim is widely available used and pretty reliable in most cases, and I like the features like the spring loaded tensioner. My oil pan is pre-tapped for one for an easier install once I find one.

My PD has already been rebuilt and upgraded once, stronger kevlar belt, better bearings, ported, custom 2.84" blower pulley, custom 6.45" crank pulley, deleted flex hose, larger air filter, custom bypass valve, etc ....it now works well for a small blower and would be a really good used blower for someone looking for low boost. Hopefully it will be worth something to someone when I get a Vortech or ATI later on.

BTW, the way you were running so lean may have been part of the reason you made a lot of peak power for your setup, as long as you weren't detonating ... lean = mean until you go boom. Maybe you made peak power around 5,200 or so before it got so severly lean up high?

Sounds like your setup will be pretty killer, what about the crank, stock? Probably ok but would concern me a little if you're going to drive it hard a lot.

 

yea im going to be keeping the stock crank. At 5600 feet above sea level, im only going to be making maybe 500 rwhp up here...it sucks being a mile above everyone else. When i dynoed 446, that was a corrected number. Uncorrected it was about 350

I drive pretty easy most of the time, but i do get on it several times every time i drive...

Ill have to post a pic of the dyno sheet, b/c it held at about 12:1 A/F ratio until 5,000 then spiked up to 15:1...the curve was linear, and the HP didnt shoot up once the A/F ratio began increasing.

Sounds like youve gotten that PD built right..how much boost are you running?

 

It's a little hard to tell with this Autometer gauge, as it reads all the way to 30 PSI so the small increments of just 1 PSI at a time are hard to distinguish ....I think it's just under 7.0 but honestly I take my last look at about 5500 RPM and it's around 6.0 there, can rev to 6500 but usually shift around 6300 if going all out. I think most people would be surprised it is merely a Powerdyne if they rode in the car, the midrange boost is pretty good for a small blower ...and the upgraded impellor speed/bearings/bypass valve make it whine about twice as loud as a stock Powerdyne, which is still very quiet but at least noticeable and sounds pleasant, just the turbine sound. My engine designer is who really hooked me up, he designed my cam/heads to work especially well around 9 - 10 PSI, where I eventually want to be ....but it still works a lot better than an off the shelf grind even at my sub 7.0 PSI level.

Being up so high in elevation sucks for you, just means you're making less power and having less fun in a way. If you plan on staying at that elevation you might want to switch to a turbo, can compensate much better on it's own without resetting boost levels. Yeah, you're stock crank s/b fine as long as it's balanced well and you don't rev high for long periods I would think.

 

yea i know the crank will be ok...im not going crazy on the boost..YET...I was thinking about going with a single front mount turbo, but I couldnt pass up the deal i got on the d1sc...anyone looking for a SC kit sould go talk to bob at exotic perfomance...i got my d1sc tuner kit with IC's for 3600!! But i really like the blower and have built the engine for supercharger, so itll stay blown for a while. Being at this alltitude does put a damper on the fun, especially when you take a vacation, take a 2000 ss for a test drive, and it throws you in the seat harder that my friends 470 rwtq nitrous T/A

Thats cool that youve gotten that PD blower built, because the major issue with that internal belt has been taken care of...i took a look at your maro and its pretty clean lookin..its your turn to get that d1sc ;p

 

LT1 350 std bore, srp pistons , eagle H-beam, 4340 crank, splayed mains, Holset 63mm turbo, stock heads, 48mm TB,no time, 124mph at 1/4mile, 98 at 1/8 mile, 3750lb with me in.

Yes, and 14 psi

HX50, that is, and stock(tunercat) computer, no good, think the head gasket went at the last race...

 

numbers in sig

 

how much boost??

 

15lbs my T-trim is maxed out (blower RPM)

 

I haven't had my 355 on the dyno yet. The torque is strong from 2500 all the way up to 6000. Very fun to drive and easy to tune. I used stock rods and crank with Speed Pro forged pistons and I'm not having any problems at all. I had all the rotating parts balanced at a local shop and it feels like a cadillac when it runs. No vibration. I haven't had to do any real maintenance to my car since I installed the FMIC.

 

update: My 355 that i described in the first post will be handling 15 psi instead of 12...with the parts in sig and the parts from my first post, will 15 psi get me over the 600 rwhp mark? I am hoping for 650 whp...what do you guys think?

Here are the parts added since it put down 446 with a bad piston
~Pacesetter long tubes with lanes true duals
~SRP forged pistons(9:1 compression)
~Eagle H beam rods
~MSD vented opti with 8.5 mm plug wires
~224/236-114 lsa .535 intake .555 exh with crane 1.6 rockers
~ported LT1 heads 2.02 int 1.60 exh
~15 psi boost