Practicallity of a long rod 352

[Guest TestZubject]

I'm in the planning stages of a street/strip SBC for my Z and have some questions. While I was looking at some possible displacement combinations, I found the article "The 350 Chevrolet should have built". I would like to build an engine displacing right around 350 c.i. and just see how much reliable power I can wring out of it. I want the motor to be streetable( I should mention that my idea of streetable has more to do with pump gas compatibility than idle quality and emmissions) and the high compression 352 seems like a natural choice for my criteria. Does anyone know of an example of this engine in the real world? Also, it seems that with a slightly more radical cashaft( maybe around 230/230 @ .050) and premium gas this engine could bump the compression up even a little higher without too much trouble. Any input would be appreciated.

[grumpyvette]

look these over, they will kick most 350 engines butt effectively

 

SBC 407

· Block, 509, +30, Zero deck, Blanked water passages, Clearanced oil ways, Lifter valley vents, ARP main & head studs, Durabond cam & Clevite 77 main bearings.

· Crank, Scat 4340 forged steel, 3.75â€, internal balance, Pioneer SFI balancer + ARP bolt.

· Rods, Comp. Products 6.00†H beam bronze bushed + ARP bolts Clevite 77 bearings.

· Pistons, SRP #4032 flat top, 5cc relief, Speed Pro plasma moly file fit rings.

· Complete rotating assembly balanced. Including - Flywheel, Clutch, Balancer & Crank pulley.

· Heads, AFR 210 Race Ready, 76cc, 2.080/1.600 valves, drilled for steam. FelPro #1014 gasket.

· Cam, Comp. Cams ‘Magnum’ #12-450-8 (286HR) Hydraulic roller.

230/230 @ .050, .377 lift 110 LSA 106 ICL.

· Pushrods, Howards Cams heavy wall 5/16†7.4†long.

· Rockers, Pro Magnum roller, 1.6, 7/16†stud.

· Lifters, Pro Magnum hydraulic roller. AFR Hydr-Rev kit.

· Comp Cams Springs #950 + #740 retainers installed at 1.875â€

· AFR rev kit, AFR stud girdle.

· Lube, Melling M99HVS pump, Canton 7qt 5 trap pan with inbuilt windage and scraper, Cooler, Accumulator, oil stat, remote filter.

· Holley 800cfm #4780C, 1†spacer, Victor Jr single plane.

· Static CR 10.32, Dynamic CR 7.9.

· Quench 0.0415†(Gasket .039†+ .0025†down hole).

· MSD Pro Billet Street Dizzy, MSD 6AL, MSD Blaster 2 coil, MSD 8,5mm leads.

 

After several pulls followed by adjustment and re-jetting we arrived at:-

 

RPM BHP Torque

3800 367.3 507.7

3900 384.0 517.1

4000 395.1 518.8

4100 407.9 522.5

4200 418.9 523.8

4300 429.4 524.5

4400 439.6 524.7

4500 449.6 524.7

4600 462.1 527.6

4700 467.4 522.3

4800 476.6 521.5

4900 485.4 520.3

5000 489.2 513.9

5100 498.5 513.4

5200 496.0 501.0

5300 506.1 501.5

5400 508.4 494.5

5500 508.7 485.8

5600 505.6 474.2

5700 505.8 466.0

5800 505.8 458.0

5900 494.6 440.3

6000 491.9 430.6

 

 

heres a 401

example 2 a 392 sbc

[Guest TestZubject]

Thanks for the response Grumpy. I had read a couple of those articles before, and I particularly liked the "getting serious" piece. So, would you be of the opinion that maximizing displacement and finding the best set of heads for the job with a matching cam are of more benfit than the higher compression and piston dwell of an equally well put together de-stroker? One of the reasons I was drawn to the 352 buildup is because I was looking to run a pretty large roller cam in an effort to move the power band up a bit to help with traction, and that motor's ability to run a lot of compression on pump gas seemed like it would help keep the engine drivable at lower rpm's as well as contributing to overall power. I've seen several ZZ4 based 350 buildups that made 500+ hp while retaining an idle vacuum of around 10 inches, which I think I can live with. I was hoping to combine their topend with the higher compression of the 352. I also ran across an engine very similar to the 401 you posted, but it was based on an LT1 and came in at 396 cu. in. Unfortunatlely that article didn't post the exact cam specs, but did refer to it as a "radical" cam. Which build path would you recommend?

[grumpyvette]

with a properly set up suspension and the tires and compounds available today if your not limited to the smaller tire widths traction is no longer a big problem. I would almost always sugest starting at the max displacement your wallet can handle as its a pretty good bet that increased displacement WITH MATCHING HEAD FLOW,COMPRESSION , and CAM timing will give good results

a few hours thought and planing and carefully matching parts to the intended rpm range and airflow requirements before buying parts makes a huge differance in results

 

btw

this crower cam has proven to give exceptional results in an LT1-4 with matching components

http://www.crower.com/misc/cam_spec/cam_finder.php?part_num=00471&x=42&y=12

 

but it requires 11:1 cpr and a 3000rpm stall and about 3.73 rear gears to get its full potential, in a 350 displacement it makes well over 500 ftv lbs of tq with some combos,in a stroker 396 LT1 based engine it would prove outstanding. that cam has proven to make an outstanding combo of hp/tq in several engines its been tested in provided those above requirements have been met and the heads have been ported, it also requires a free flow headers and exhaust

 

you want LT1/LT4 info? we got info

 

http://phil.tobin.net/Hoover/top.html

 

http://www.h-body.org/people/projects/building_lt1/lt1%20info.html

 

http://www.gmmodernmuscle.com/383/383build.html

http://www.idavette.net/winback/lt115.htm

 

http://www.afrashteh.com/guide/install.htm

 

http://www.corvettefever.com/howto/36501/

 

http://www.protechmachine.net/lt4/lt4.html

 

http://www.thunderracing.com/lt1inteng.htm#CNC

 

http://phil.tobin.net/Hoover/index.html

 

http://www.gmmodernmuscle.com/383/383build.html

 

http://www.h-body.org/people/projects/building_lt1/lt1%20info.html

 

http://www.automotiverebuilder.com/ar/ar99928.htm

 

http://www.hashmarks.com/dyno_page.htm

 

http://www.mochevracing.com/Corvette/lt1lt4.html

 

http://www.lt1motorsports.com/396LT1.htm

 

http://www.lt4.com/story.htm

 

http://www.malcams.com/legacy/misc/headflow.htm

 

http://www.kendrick-auto.com/lt_1__gm_head.htm

 

http://www.charm.net/~mchaney/optisprk/optisprk.htm

 

http://www.fierolt1.com/lt1_95_up_OptiReplace.htm

 

http://www.noid.org/~muttvette/opti.html

 

http://www.gulicks.com/vette/projects/opti/index.html

 

http://www.houston-f-body.org/tech/optispark/

 

http://www.dynotech-eng.com/dynaspark.htm

 

http://www.corvetteclinicinc.com/

 

http://www.corvettefever.com/howto/16758

[Guest TestZubject]

Wow! Lots of good info Grumpy. The more I read up on the LT1 the more attractive it becomes, though I have to admit it is tough for me to overcome my affinity for large bore short stroke engines like the 377 or 352. I would really like to build an LT1 396, but I just don't think I can swing ~$1000 for a billet stroker crank, on top of the cost of the forged rods and pistons that I would like. Maybe a .030" over LT1 with a large cam and some AFR heads with a little port work would be the way to go.

[ssparko]

I am planning to build a long rod 352 to replace my 327. I am hoping for 450-500hp I want a quick revving motor, and I want to rev it past 6000 occasionally. I am wondering if my cam choice is a decent one for this combo. I would think that so long as I have my rotating assembly balanced I should be able to rev far beyond the 6000 or so red line of the typical 400 because this setup is internally balanced and should put alot less stress on the mains.

 

400 block .030 over (Got it)

JE forged pistons with .125 compression height

6.250" rods - Debating between H beam or Light I beam

327 forged Large Journal crank (1130)

Dart 220CC aluminum heads 2.10 intake 1.625 exhast (Got em)

Edelbrock RPM Air Gap intake intake

COMP Cams #12-677-4 Small Block Chevy XTREME ENERGY XS 274 S Mechanical Flat Tappet Solid Camshaft SOLID: Very strong mid-range, torque & throttle response, 2200+ stall.

1.5 Rockers

T56- Transmission (Got it)

 

Thoughts?

[rsicard]

Wow! Lots of good info Grumpy. The more I read up on the LT1 the more attractive it becomes, though I have to admit it is tough for me to overcome my affinity for large bore short stroke engines like the 377 or 352. I would really like to build an LT1 396, but I just don't think I can swing ~$1000 for a billet stroker crank, on top of the cost of the forged rods and pistons that I would like. Maybe a .030" over LT1 with a large cam and some AFR heads with a little port work would be the way to go.

 

No port work needed with competition AFR heads. Go to their site and look at the Dyno runs to get an idea of parts combinations to achieve 500+ HP on 383 cu in. Use light weight JE SRP professional pistons, SCAT crank and I beam rods. Ceramic coat piston crowns, Zero deck the block and use thin head gaskets for best quench. Go to Solid Roller Lifters, aggressive camshaft lift/duration and 1.6 ratio rockers. Intake Manifold ports to match heads. Easy to achieve 500+ HP and TQ.

[luigi]

I have one in my Z. Good engine. Cranking compression ~225 psi. Calculated compression 11.2:1. Runs fine on 87 octane. Dynoed with 93 octane @ 518 bhp ~430 lbs. I love it. We quit at 7600 rpm. Was still at 500bhp.

Use a 6.125 rod (K1 makes a good rod) I used an Eagle SIR. If a 6.125 rod is used an off the shelf piston with a reasonable comp. height can be used. Cam in that one was 248/252 @ .050. .406" lobe lift. No real draw backs, and cheap to build. I used a cast 307 crank for the first one. Turned the counterweights down round. Close the quench up as tight as you dare. I ran .026". Opened it up to .036".

If you have any questions PM me

Lewis

I just noticed it says I'm a newbie. I think that happened on the change over. Kinda funny.

Edited February 22, 2011 by luigi

[Michael]

At that level of performance, why not consider a mechanical roller cam?

[ssparko]

A couple of reasons.

 

 

1. I'm not a Wall St. banker or a public sector employee (I'm poor)

 

2. The heads I got off of Craigslist for $650 and they had just been completely gone through with new springs etc, but the springs are setup for flat tappet cams. I don't want to spend the money for new springs (See #1)

 

 

If I win the lotto I will do a solid roller cam!