V8 questionsBuild

[John Scott]

Since my thoughts have turned V8, I'm going to throw out a few questions.

6" rods fact or fiction? I've read plenty of articles that say the 6" rod provides little if any hp gains. Others claim big increases. The physics claim a more "effecient" combination. Most of the experienced engine builds swear by it. Worth it? After the last few hp, maybe. Read www.Iskycams.com/techtips.html#2005 among others. Tell me what you think. I'm considering it more because of the kit's neutral balance and ability to use my 3.58" bolt circle flywheel.

Would a smaller head, say 195 cc be better for velocity, than 210 at higher altitudes?

I see some huge torque #s using smaller heads that flow big #S like AFR. My targeted rpm range will be in the low 6000s.

Fast Frog brought up the issue of oil ring lands in the wrist pin holes. I see many stroker pistons have this feature. A concern for a street engine?

 

JS

 

[ July 15, 2001: Message edited by: John Scott ]

[pparaska]

Ed Isky is no one I'd discount.

I agree that the 6" rod is more like a "fad" thing than maybe is needed, and for the street at 6000rpm max, probably not worth any improvement. The only thing that intrigues me is octane tolerance increases that I've heard about from larger rod/stroke ratios.

[Guest Anonymous]

Agreed, Isky has some good information on his site, his tech. FAQ is very good. The man knows what he talks about, that is obvious.

 

Regards,

 

Lone

[Kevin Shasteen]

I agree w/the Ed-miester & that he knows what he's taliking about.

 

However, he did mention & agree w/the longer dwell time...and this effects timing/that has always been the intriguing part for me when discussing longer rods! A longer rod also moves the piston higher up towards a "0" Deck block-this helps airflow during combustion-thus an optimum combustion will result in less advance in timing which makes for a more efficient engine.

 

I'ld never want to use a piston where its pin has been moved up into the rings; unless I was racing & had full sponsership who'ld flip the bill for an engine rebuild every week or after each race!

 

If the fuss about longer rods were soley intending to give you "MORE HP/TORQUE-then I agree...its a lot about nothing as the gains would be minimal; the dwell time is for timing mostly & not about the extra hp/torque.

 

Kevin,

(Yea,Still a "Short Rod" Inliner)

[Guest Night_rider_383]

The main fact with longer rods is that the piston to bore side loads is cut down (rod/stroke ratio). This gives you less wear on the cyl. its self, piston, and ring package. The longer rod its self really wont even give you 5 hp but the part to this is the fact the piston dwells longer. That can help build hp, plus will let you add more timing and compression to the engine. Is it worth it? To me yes but only if i had the extra money to put into the rods/pistons. The wristpin/oil ring land prob. I feel this is not much to worry about on a street engine where rpm is under 6k. I see the biggest prob with the oil land would be up higher in the rpm band where the piston speed is more along with the force put on the rings, pistons, rods. I would stick with under 200 cc heads for street. The larger cc heads will flow better at high rpms but you will lose lower rpm torque. 195 cc is real good for a high performance engine that is used from idle to 6k

[Mikelly]

I spoke with Ed and Company about my engine build and we used 5.7 rods rather than go with the 6 inch rods. Everyone I spoke with during my investigation process told me exactly what is being stated here... 6 inch rods are nice if you plan 7000RPM shifts, but don't realy ADD power, but help with side loading at higher revs. The guys at Isky are sharp, informative, and well versed in small block chevy builds.. I spoke and e-mailed back and forth with them several times during my build process and they actually expressed interest in seeing my car when it is done, before I go to the Silver State Challenge...

 

Mike

[Guest Anonymous]

hey mike I didn't know your planning on doing the silver state run too when do you plan on doing it?? I'm shooting for the year after next if all goes according to plan.

 

[ July 18, 2001: Message edited by: v-8 Zfreak ]

[Mike C]

The biggest killer of low speed torque is cam selection over cylinder head intake port volume. The Iron Eagle 215s make more average torque below 4000 rpm than the 165 or 180s. Big valves seem to help torque at low speeds rather than hamper it. If running Iron heads, go with the Iron Eagle 215s. If using aluminum, go with AFR. 190 if running a dual plane intake and 195 if running a Victor Jr.