I want to build a stronger bottom end with all forged components. I still want to stay with stock stroke but will go with 6" rods this time. I want light weight components and am seriously considering turbo or supercharging. My goals are still the same, this car will still be a regular driver so driveability and mileage are still the prime concern. I want to go with an aftermarket pan and related oiling components that will be suitable for track and strip as well as for normal driving. Some of this will be new territory for me, I'm listening....

 

My motto is, the only substitute for cubic inches is rectangular dollars. Even if you are insistent on staying with a 3.48" stroke, you might consider a 4.125" bore. Another consideration is a good quench area. Even if you go with a low compression ratio because of the boost, a tight piston to head clearance will pay off...especially under boost. A 3.50" crank would save taking .010" off the deck for the same results. Myself, I'd like to see you go bigger. Just a few thoughts.

RACE ON!!!

 

The reason I'm not interested in more displacement is for maximumizing mileage and the fact that I'm not looking for any particular power level. I know it will be fast, it already is. I do find the 3.50 crank idea interesting.

 

My 385 just got 33 mpg on my last highway trip in 6th gear @ 2000 rpms (3.73's). These cars are truly amazing!

Mike

 

I get over 25 with my 396 on extended trips. But at 1800 RPM with my car the resonance drives me batty. So I drop her in 5th at times to get the Rs up to 2000 or so to give me some relief. A 6" rod 350 would also run well. Especially with some boost behind it I remember a few years back Hot Rod magazine built a big bore short stroke 350. Using a 3.25" stroke crank and 6.375" rods if my memory is correct. The cam was relatively mild and they used a set of AFR 195 heads running a final compression ratio of 11:1.

With the rod combo HR thrased this engine on pump regular and this engine made over 400+hp and tons of torq. The rods that they actually used were from a Ford 300 six cylinder engine. They had to be machined to fit the SBC crankshaft. The crank that was used was a 327 SBC steel crank. That same engine also got well over 20 MPG as well.

 

www.speedomotive.com sells the 360 crank kit. I believe this is the 3.50 crank kit. Circle track guys love this..

 

TJ, you are right. I still have a copy of the article. The amazing thing with the 3.25 short stroke, long-rod, big bore,(still 350 cu inches), 11:1 high compression was, it made the power output on 87 octane with no hint of pinging. They attributed most of that to the ultra-long rod to stroke ratio:1.90:1. I keep eyeballing Speedomotive's kit for a very similar rotating assembly, 3.25 x 6.250" or 6.20" rod. Sounds like a great compromise in this time of gas prices, low octanes and the desire for power.

 

I just did a 6"rod SR 358 awhile back. Can't wait to hear that beast run!!


Yes, it stays indoors

 

I'd like to hear more details on that block project, brands, weights, etc. I really appreciate all the input so far. What kind of CR should I be considering if I go super or turbocharged? Can I still use fairly light rods and pistons as long as they're good quality? I've always heard that a turbo will get you better mileage than a supercharger, is that so? Should I consider something besides my Hotcam if I use boost? Thanks all.

 

You need to decide "for sure" if your gonna turbo or supercrg. This makes all the difference in how you build the motor. Forced induction needs a CR around 8.5 or 9/1 so you can boost the heck out of it. If you go NA then try for 11/1. Remember that boost cost major money, take a look at the FI forum, nobody sells a EASY bolt on kit.

 

Yeah I realize that. I'll definitely make that decision before I start buying components. If I stay with NA I'll probably go to 11.5 or so. I'm currently at 11.3. I've seen pics of superchargers installed on LT1s but where in the hell would you mount a turbo? I know it's been done but I've never seen it. Actually, I've got an almost new turbo for an engine of about 5.9L displacement. I guess I should dig it out and do some contemplating....

 

Scat 4340 crank
Manley Sportmaster 6" rods and pistons(Those pistons are LIGHT)
Custom ground Comp SR 250/254 @ .050, .670/.660 lift, 110 L.S. adv. duration-I'dhave to look at my cam card. Around 284-288 or so.
Dart Conquest (early Pro-1)200. Flow just over 300-I can get the flow sheet if you like. The low/mid lift numbers were impressive also.
Team G thoroughly worked over plenum, lots of angle milling on heads/intake!!
0 deck, 10.5 comp.
1.6 Jesel SS series shaft rockers
All the usual BS-Screened/epoxied, ported oil pump/passages, studded bottom end, etc.

 

When you get a chance, could you PM me with part #s on the rods and pistons? Or you can post them here if you wish. Very interested in the actual weights. Thanks, Chris

 

I'll have to look them up for you. May take a few days. I started building it around 9/11 and finished it last year. Most of the reciepts are long gone. Off the top of my head I think the pistons were 398 grams. The skirts are short and pretty thin. I'll have to look these up..
Wish I could have dyno'ed it. Ran out of $$. The person who did the heads and spec'd the cam is hoping for 560-570 @ the crank on pump gas.
You have a PM btw

 

Got the cam card--
Part #12-000-9, Grind # CS 4126S/4152S R 110.0
Cast gear valve lash .026 on int. and exh.
Gross valve lift (w/1.6 rocker).665 int, 648 exh.
at .050:int open@19 BTDC, close@ 51 ABDC
at .050:exh open 61 BBDC, close@ 13 ATDC
Installed @ 106 intake centerline
250/254 duration at .050, 110 lobe center.. (ramps are slightly inverted)
Springs 200#and #500, installed height, can't remember for the life of me. More to come

 

That's only a few grams more than the hypers I'm running right now, not bad. Got your PM and replied, thanks.

 

I'm also getting 25-28MPG on long trips with mine, but would agree on the resonance between 1700-2000RPM on mine. Maybe time for that custom Corsa system...

Ron

 

[SNIP=CFI-EFI]My motto is, the only substitute for cubic inches is rectangular dollars. Even if you are insistent on staying with a 3.48" stroke, you might consider a 4.125" bore. Myself, I'd like to see you go bigger. RACE ON!!![/SNIP]

ABSOLUTELY!

Based on the constraints you listed - driveability, etc., - 1.0 to 1.1 HP per cubic inch (NA) should be about what you can expect.

If you do the math, you'll see you'll end up with much more power by starting off with more displacement and the engine won't have to work as hard.

Jake

 

Well I'm already well past that at my current level of build. My dyno runs from last year put me at 408 computed CHP. I've installed much better headers and exhaust since then and corrected a couple of little problems that were present at that time. Jake, I just recently became aware of your race engine experience during another recent post that we both contributed to. Do you have much experience or knowledge of forced induction builds? Either way, I welcome your input as well as everyone else's. Should I decide to go blown, I'm very interested in knowing how light I can go with rods and pistons and still have bullet proof durability in an everyday driver. I like CFI-EFI's idea of the 3.50 crank. How do you accomplish a 4.125 bore with a 350 LTx block?

 

I've always been against any form of artiifical, let me change that, add-on power producers. That includes NOS, turbos and superchargers. I'm a cubic-inch-and-attention-to-detail-for-power man. So, no, I have no personal, hands-on experience on working on them. My expereince is that sooner or later they blow up though.

So now what I'll get are posts from guys saying "I've been running blah, blah, blah . . ." or "I know so and so who's been running blah, blah, blah". . ." or if you build 'em blah, blah, blah . . ." Fact remains, sooner or later they blow up. End of story.

If I got hit by ligntening and had a mind fart then decided to one day build one, I'd be thinking big, strong and heavy in my parts selection.

Big springs, strongest rods/bolts/pistons my bank account could stand; Bow-Tie block with 4 bolt mains on all five, not just the center three; forged pistons with really thick decks, lots of piston to wall and heavy walled pins; 5/16ths rings with huge end gaps; "O" ringed block deck, internally balanced top-of-the-line forged crank with full counter-weights and NOT lightened, Jesel shaft rocker setup, extra cooling capacity, etc., etc.

I'd let torque do the work and go no higher than five grand in Rs.
Steel wherever I could put it (like in my rocker arm selection), low compression, timing and RPMs.

Then I'd have to start signing checks for driveline stuff; the trans won't live, the half shafts and drive shaft will soon be history along with the ring and pinion. Torque's a parts killer and what it doesn't kill right away, a momentary lean A/F ratio will take care of.

To pump up the power with an adder, you've got to think STRONG everywhere including the driveline; not light; that adds up to lots of $$$ too.

And no, I'm sure he didn't mean you could get 4.125 bore out of a 350 block; you'd be pushing it to go .060. His point, I'm pretty sure, is the same as mine; that it's much easier to get higher power when you start off with lots of cubes.

If I was in the market for lots of torque and HP, I'd do whatever I had to and drop a 540 BB in mine. I'd still have the drive line woes, but I wouldn't worry that the engine would gernade on me.

Just my thoughts.

.Jake