|09-03-2013 09:51 PM|
|09-03-2013 07:43 PM|
|bfritch||Sorry the cam was 234/238 on a 112 lsa. Same cam as the 2204 for the factory roller block. I strongly believe this cam uses crane cam lobes. I looked it up in their master lobe list. Same .004 and .05 durations with the same lift.|
|09-03-2013 07:32 PM|
|bfritch||I'm now looking into a 406 or 427 SBC short block, 10.3 and 10.0 compression (based on 64cc comb chamber), respectively. Will be using the same E-Tec 170cc heads and air gap intake. Super Chevy did a series called "Major Mouse" using a 427 cu in with 11:1 compression, same heads and intake and the cam an edelbrock 2201 cam 234/239 .539/.548 with 1.5 rockers but they used 1.6 rockers. The result was 512hp at 5400 rpm and 570tq at 4000, with more than 500 tq from 2500 to 5000 rpm. This is the type of power band I'm looking for. Would I be nuts to try for something similar with the 427 block? I was told the 170cc heads are just way too small for that many cubic inches, but look at those numbers. The article I mentioned was from the April 2005 issue of Super Chevy.|
|01-18-2013 07:40 AM|
|BuzzLOL||.. The 350HP 350" GM 'RamJet 350' crate engine uses an amazingly small 196/206 duration @ .050" lift 'granny' cam!|
|01-17-2013 08:41 PM|
|bfritch||I don't know...darn the optimistic magazine articles.|
|01-17-2013 08:32 PM|
|vinniekq2||a 206 duration/450 lift cam? what would that net HP wise?low 300s?|
|01-17-2013 08:19 PM|
|bfritch||Yes SS I agree. The cam duration and comp ratio relationship is relatively new to me and I'm just recently learning about DCR. Too bad about those unrealistic engine combos because 442/495 from a 206/206 cam in a 383 sounds really nice...too bad it would need race gas. I need to familiarize myself with calculating DCR so I don't ever assemble mismatched components...|
|01-17-2013 08:09 PM|
One thing in particular in the article about the "11.5:1 CR"??? engine that caught my eye was how did a cam with an almost 10 degree later IVC point create more cranking pressure? (cam tests 1 & 2)(220psi vrs 225psi) Must have been a typo right?
Also that it wasn't a very realistic comparision to real world street application as the smaller cammed engines dynamic compression would be way too high for pump gas as previously mentioned & IMO. I'm sure your aware that the compression should be lower for smaller duration cams, and higher CR for long duration cams, so that by just swapping cams its not really a valid test of potential, just demonstrates that longer durations move peak torque up in the rpm range. Also that since the compression wasn't optimised for each cam average power/torque numbers are misleading IMO.
|01-17-2013 08:05 PM|
|bfritch||True true true, so many combinations and possibilities. I know the general consensus is that AFRs are the best off the shelf wouldn't mind having a set myself.|
|01-17-2013 06:57 AM|
.. Oh, OK, sorry, thought you meant the article linked to in that posting...
.. AFR stands for Air Flow Research and their heads usually outflow right out of the box other brand heads of the same size... as their name suggests... by better port shape, not bigger size... and they can be optioned with CNC porting to improve them even further... (but also enlarges them slightly)
.. Well, we don't know if the 170cc e-Tecs are superior to the ported iron 882's in that article because I don't think many details about the porting job were mentioned... or even the name of the porter... the power numbers in the article kinda suggest the ported 882's may flow better than the stock e-Tecs..!! And I assume close attention was paid to compression ratio/deck height/quench... Unusually good numbers for such a small cam(if not helped by a 'happy' dyno)... The ported 882's (165cc stock?) may also have ended up quite a bit bigger than 170cc... and the port shapes focused on torque... I've also seen articles where ported stock Chevy 461X heads make 500+HP...
.. If iron and aluminum heads have identical spec.s/ports, the iron heads usually make slightly more power, because the aluminum bleeds off heat faster... and we're talking 'heat engines' wherein heat is power... of course, iron heads can 'heat soak' after a few seconds of high power and loose power then... whereas the aluminum stays cooler, giving off the heat to the coolant... and the aluminum heads are lighter, meaning less power needed to move the vehicle...
|01-17-2013 06:36 AM|
|bfritch||Thanks Buzz, I def don't want to get into something that required an octane boost if I can avoid it. Yes the 11.5:1 comp ratio is a bit high and the cranking pressure of 230psi on some of those combos sound like detonation even on 93 octane. The article I was referring to in my last post was the article that you posted just prior, the 350 that used the old iron (882 I think) heads and a small flat tappet cam. The article you're talking about is from my first post, the 383 using the 190cc trick flow heads. Now I know the e-tecs are superior to the old iron heads but as for the trick flows I really dont know. However, I do like the small port heads for throttle response and low speed torque, which like you say with those heads on a 400ci would be an excellent combo.|
|01-17-2013 05:31 AM|
.. Yes, 1960's factory 383 - 390" engines were rated about that 420-440 torque, but a little less HP with the poorer flowing heads and usually smaller valves back then...
.. Are you saying e-Tec 170cc heads are superior to the AFR 190cc ones used in that article? (they're not) And, of course, the power/torque numbers being a bit higher than expected is because of the usually not seen 11.5:1 compression ratio...
.. The 206/212 cam they are using has unusual timings, like intake opening at -3 instead of around the common +6... kinda like Thumpr cams use unusual timings to help compensate for the narrow 107 degree LSA and not totally lose off-idle power...
.. The Comp 206/212 cam is very close to the GM ZZ2 - ZZ4 350" crate engines roller cam of 208/221 .474/.510 lift... which usually can be easily found used on eBay, Craig's List, or at swapmeets... I bought one a while back for $125 with the roller lifters... those 350's were 345-355Hp depending on C.R. and ~380-400 torque... HP limited by -113 165cc stock GM aluminum heads and basic stock type 1.94"/1.5" valves... of course, same cam in 383" with bigger valves/heads would make for bigger power numbers...
.. Like I keep saying, if really want 500 lb.-ft. torque and smallish cam/very low RPM big torque... a 400+" engine is the way to go... a SBC 400 is an overbored '383' right from the factory... a particular cam and heads make about the same HP no matter what size engine is under them... but, torque peak goes up with cubic inches and also up somewhat with compression ratio... and a milder cam can be used for better MPG... and, it's hard to go very high with static compression ratio with a smallish cam because dynamic compression ratio starts wanting higher octane fuel... so may need premium gas plus octane booster... which is OK if you don't mind adding the booster... the 11.5 C.R. 206/206 cam combo they did first prolly wanted racing fuel, although they don't mention anything about fuel used as I recall... I simply add an ounce or two of kerosene to a tank of gas if a combo gets into spark knock... or I get a batch of low octane gas by mistake in a stock engine... kerosene is about the same price as gasoline and is also a fuel, so doesn't really add any expense... I put it from a gallon container into handy used empty red plastic 12 ounce octane booster bottles and keep one in the trunk... and in my boat...
.. This Hot Rod 383 article also gets into big torque, but they eventually go to a bigger cam than the 196/206 duration they start with:
http://www.hotrod.com/techarticles/e...p/viewall.html 500 lb.-ft. from 383" stock Vortec heads (flywheel dyno)
http://www.hotrod.com/techarticles/e...s/viewall.html Vortec vs Eddy E-street heads 383" (rear wheel dyno)
|01-11-2013 07:24 PM|
Thanks ap72. That's what I'm hearing.
Buzz take the same concept as that magazine article and use a comp roller XR258HR 206/212 .480 .487 110 with the same compression and some better heads like the e-tec 170 or vortec and should it not do better both HP and TQ? I would think something like 380/440 with a similar powerband idle to about 5000-5200.
|01-11-2013 09:52 AM|
|01-11-2013 09:37 AM|
.. Here's a short duration (204/216), good HP, good torque, 'budget' 350 build... much less expensive parts could be substituted for some of the 'budget' parts it uses/tries to sell you... mainly relies on really good porting of stock heads and good quench...
Chevy Small Block Build - Mildly Amusing - Super Chevy Magazine
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