revised parts collection

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Jan 21, 2005 | 09:58 PM

panchop

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Melting Slicks

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From: mesa,az

revised parts collection

between you guys and the chevelle guys i made a few changes. canceled an order there, a new one here. this is what i have gathered up now. i will start assembly in a month or so. waiting for a few things.
454 2 bolt block converted to 4 bolt bored .60 over
SCAT Lightweight ProComp 4.25 stroke Crank
Scat Upgraded H beam 6.385 con rods
Pro Topline aluminum 360cc port modified heads
going to be using flat top pistons for about 7.5-8 comp
Isky solid roller cam 640/650 304/318 252(?)/264 112 LSA
Isky 1..75 roller rockers
Isky pushrods
Isky springs
Isky Red zone lifters
weiand 871 blower Kit 12% under drive
Only thing I haven’t ordered/received are the pistons
I'd like to make at least 700HP by 6500.
What do you think?

Jan 21, 2005 | 10:48 PM

comp

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From: eville in

sounds Good

Jan 22, 2005 | 12:07 PM

SWCDuke

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The cam has too much overlap for boost- 116 LCA is more like it. Too much overlap bleeds off boost pressure until very high revs and doesn't help at the top end since inlet pressure is positive. Some cam manufacturers offer cams that are set up for boosted engines, and they have less overlap on a given duration than a cam for a natually aspirated engine.

You'll need a very efficient set of exhaust manifolds (long tube headers are useless and can even be detrimental on boosted engines) and at least 3" exhaust piping and very low restriction mufflers to achieve anywhere near your power goal.

With a 4.25" stroke mean piston speed will be 4600 FPM at 6500, so you're closing in on the 5000 -5200 FPM limit on botton end stress and aspriation efficiency that F1 and NASCAR are up against.

Duke

Jan 22, 2005 | 03:28 PM

panchop

Thread Starter

Melting Slicks

Joined: Dec 2000

Posts: 2,130

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From: mesa,az

the cam is a custom grind from isky, they for sure know it's a blower engine but monday i will call them and make sure on the LCA. The deal about piston speed, well when i was first discussing strokes. weather to go with a 3.75, 4.0, 4.25 i asked about piston speed as it had always been a limiting factor on the old harleys i used to play with. the general relpy as i groked it was i was thinking old technology ,new and improved materials made it a somewhat moot point. not disagreeing with you just kinda laughing that it has come back to my originial thoughts. So about 5000FPM I'm gonna start tweaking stuff.
thanks
greg

Last edited by panchop; Jan 22, 2005 at 03:36 PM.

Jan 22, 2005 | 04:18 PM

cardo0

Le Mans Master

Joined: Oct 2002

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From: Las Vegas - Just stop perpetuating myths please.

Overlap with a pos press induction? No.

Always heard of wide LSA used for blowers and turbos. Need to have the exh vlv shut before the int vlv opens and pushes fuel out the exh pipe.
Yea better double check that cam.

Blowers need a dedicated cam or the motor may make less power than without the huffer. Supercharging is bit of a science itself and take custom ignition curves too and even relief vlvs. Very easy to blow the charger off the mtr. I've never installed one but couldn't resist and picked up a Street Supercharging book signed by the author at a swapmeet. Sounds like u may need a better information source.
Caution.

cardo0

Jan 23, 2005 | 01:32 PM

panchop

Thread Starter

Melting Slicks

Joined: Dec 2000

Posts: 2,130

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From: mesa,az

OK you guys got me doing a bunch of research. seems Weiand, BDS, and the book Street Supercharging all recommend a LSA of 112-114 degrees. ( BDS then tells you best performance on gas will be at 110* in the same paragraph but... ) Seems the reason for the narrow LSA is the size of the blower. After that they all call for a split duration cam shaft with 10 to 12 degrees more duration on the exhaust. i will call to check my numbers with Isky monday but I think Its gonna be allright.
Thanks
Greg

Jan 23, 2005 | 05:53 PM

cardo0

Le Mans Master

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From: Las Vegas - Just stop perpetuating myths please.

Sounds like ur on the right track.

Timely review. Didn't want to see u blow ur top off after all that effort and investment.
And i can c from ur post on carbs ur gonn'a cover all the bases.

I'll jump onto that post to give my 2 cents there also.

Good luck. Big learning curve ahead of u.

cardo0

Jan 23, 2005 | 09:28 PM

SWCDuke

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For the amount of money and time you are investing in this project I would seriously recommend that you get yourself a good engine simulation program like Engine Analyser and do some real system engineering. If you don't, you really WILL only have a "collection of parts".

Here's some food for thought. LSA without duration context is meaningless. As you increase duration at constant LSA, overlap increases CONSIDERABLY. Do the LSA recommendations is your book relate to a specific duration or range or durations? You actually need to know where to index the centerlines of the inlet and exhaust lobes. LSA without the context of at least one centerline is also meaningless.

Duke