Fact: You can't have it both ways (i.e., suspend the pipedreams).

 

Five7,
Respectfully, I think this kind of stuff has a ton of technical merit. What we thought was "the standard" changes with the advent of new technology. I prove it to myself everyday, with my IROC. My carbed combo makes just short of 300 at the wheels and can still pull a 15/19 mileage combo with a 4:10 gear. Granted it has a 5 speed but that's the point. With a six speed and fuel injection, I bet I can improve mileage and performance. I just hate it when we define terms as constant, then nobody wants to test the waters. Remember when 300 HP was the standard for a good street motor. Jeez...you could fall of a log and make 300 now. "Necessity is the Mother of Invention". There is a need for this technology. Companies and enthusiates will step up to the plate....believe me.

 

Does it rev to 7500 RPMs? Do you know of a single SBC that revs to 7500 RPMs that is in any way definable as "for the street"?

I'm not saying you can't try something new. I am saying that pulling numbers out of the air and assuming it is possible is unrealistic and a receipe for disappointment.

To quote the original premise: "i want to do a 302 with about 400 hp and a 7500 redline for the street ." Where did those #'s come from? Why a 302? Why 400 hp? Why 7500 redline? How do you define "for the street"?

You can build a 400 HP 302 that doesn't have to rev to 7500 RPM. You can build a 302 that revs to 7500 RPM. Whether you would want to drive either daily on the street in a 3600 lb 3rd gen is debateable.

Whether a street 400 that had the same money put toward it would blow away any of the above 302's is not open to debate.

Neil87Z28 said it all from first-hand experinece. The originator is going down a path that worsens what he has.

About your "tech" and "EFI" points, I further quote the originator: "i dont wanna use an ls1, i wanna go carbed and use my 4 speed and 4.10 gears ." Again, out of touch with reality. In touch with 7 mpg while taking it easy and getting blown away at stop lights by Accords when not. Not my defination of "for the street".

The laws of physics are constants. You can work with them to improve what's been done, or you can let them work against you.

 

Ahh...it's the 7500 rpm issue. I see your point.

 

wow , this is a good thread, some good info and some good points from you guys . Well heres the thing , i am using a 4 speed , not a 5 or 6 , dont really care about streetability as in like needing to idle for 10 min by itself things like that or gas mileage. this is my fun car , less than 3k a year . I have a 2000 deville for daily running around so there my practical . I just thought it would be cool to have an engine that will spin to 7500 , many 350s can spin to 7000 but i just though it would be cool to have one spin to 7500 and if i was having an engine built i would want it that way . The reason so high too is that i have a 4 speed , which = 1:1 4th gear and small 25.6 inch diameter stock height tires. That would keep me in the 4000 range cruising and right in the power. The reason i thought a 302 was because i didnt realize anythign else would spin that high . I dont wanna spend 10000 on this enigne i was thinkin more along the lines or 6-8 . I thought the 302 was the only way to do it cheaply . see my father is into pontiacs , hes has a 77 ta with a 462 pontiac , so he doesnt know about chevy or care . So the highest his engine sees is the occ 6000 but usually 5800 . If i knew i could get a chev 350 to rev that high i wouldnt get rid of that idea. Also im not a fan of the 400 block , i hear theirs some problems with the block like water jackets and cooling issues and i just dont want a 400 . rather go 383 if anythign but then that wont get me high rpms. As far as racing o yeah i will drag race it but how many times a year maybe go to the track twice if that . And i never get any street races anyways so i aint worried about that . thanks for the info and lets keep this thread open .

 

i think what everyone is forgetting is that the original "DZ" 302 redlined at 8000 rpm because it had to. In those days you made power with duratiuon, because cams were archaic and so were heads. ANY aftermarket head will out flow the "Turbo" castings. If i'm not mistaken you had to use the stock block and heads in transam racing which was why they were built in the first place.

if your just looking for an engine capeable of spinning to 7500, its not so bad. My 383 is revlimited to 6200, should be fine to 6500. thats with a cast steel crank and economy rods. If you want peak power up there (7500) it will be a complete dog down low. As you mentioned there is no NEED to do this with a 302. a 350 will do it just as well, the stroke isn't a limiting factor at that speed. My friend used to spin his 2 bolt stock internals 350 to 7000 on a regular basis with a long duration hydraulic cam.

 

You can get plenty of engines much larger than a 302 to rev to 7500. My buddies 383 revs to 7500rpms, yeah its not very streetable, but it can be done and probably just as cheap as the 302 you're talking about. Big inches doesn't mean you can't have big revs.

Shawn

 

im built a motor for my firebird and its a 307 sbc bored .060 over stock crank and rods with 10.7:1 compression pistons a solid roller cam dart heads roller rockers and stud girdles single plane intake and 780 holley it runs 11.98 in a 1/4 with 4.10 gears and th 400 tranny 3500 stall with a transbrake

 

Why would you build a 307 like that? Just out of curiosity. Plus timeslips help.

 

the short block was free from my friend so i put new rings bearings and freeze out plug and built it up he had it in a chevy s10 that ran 10.33 with 125 shot i knew it was a capable motor and because he ran nos on it thats why i freshed it up

 

Six to eight thousand is a healthy budget. Let's spend it!! I'd go this route. NASCAR discards are cool. They are superlight and durable. http://cgi.ebay.com/ebaymotors/BRYAN...QQcmdZViewItem This one will probably end up going in the 6 to 7 hundred dollar range. Then some custom JE flat tops with Total Seal Max Seal Rings, $1000. These NASCAR assemblies come with a big block snout. $400 for the proper ATI balancer and the proper front timing cover from CV Products, $200. The correct double row true roller from Cloyes, $150. Let see, a set of 100% CNC ported 195cc AFR's, $2000. A Jesel Sportsman Shaft rocker assembly, $800. Crane Street Roller solid roller cam assembly, $1100. A Moroso pan, crank scraper and windage tray, $200. Your at $6500 now. How about machine work...the works including torque plate honing and converting to four bolt mains (assuming you are using the prerequisited small journal, 4" bore block). A half fill of HardBlok for good measure. Hooker 1 3/4" headers. A Victor Jr intake and 750 Mighty Demon. I think that's it. Man, that was fun!!! You can just hear this baby screaming!!!

 

making the power on a 302 is easy as wesilva has said. the 50 less cubes made by removing the stroke from a 350 can easily be "regained", in combustion efficiency terms, by using longer rods such as 6.25". the milliseconds of piston dwell in the 20 degree before/after tdc range allows for use of a higher compression ratio such as 12.1:1 0n 93 octane using extremely high velocity ports and state of the art chambers of the 14 degree bowtie heads. this enabels you to dial OUT timing to prevent knock at lower engine speed at higher loads such as cruise or lugging the engine.no more than 32 degrees total timing by 4500 should be right. dont forget to use colder heat range plugs gapped to about .025" using a capacitive discharge type of ignition with a 10mm plug wire set. typically on a "street" engine with lower compression ratios (8.5-11.2)you needed to run a longer firing cycle with the biggest flame kernal possible(large gaps) to make up for poor cylinder firing and incomlpete burn. the internal operating conditions now dictate forceful and PRECISE timing. ive personally made more than 710 fwhp with a "similar" bore stroke combo. we used a 4.155" .030 bore 400 block and 3.25 stroke from the 327 the rod was longer than 6.25 inches(don't ask, won't tell). the rod to stroke ratio computes well when compared to the bore stroke ratio..( think lamborghini engines). it idles smoothly at 900 and redlined at 7700. th tone of the engine was nothing like ive ever heard before. very close in sound to nextel cup restrictor plate motor. we custom made headers to fut the chassis and built in the ability to make the primaries longer and shorter to optimize exhaust gas speed for the given used rpm range (2500 rpm launch to 7200 shift point) before finalized construction and coating to control temp of flowing gas and reducing inherant heat in engine compartment (take notice of how broad the usable torque curve is). i cannot divilge more specific data at this time. i can offer that block/crank prep and machine work is critical in keeping this engine alive at these sustained rpm levels. a 2 bolt block modified to splayed 4 bolt center caps is very smart money spent. for "street use" no need for block fill yet having the block line bored is critical in locating precise and square bore centers relative to the crank then followed by the smallest overbore possible to retaincylinder wall thickness. follow the proceedure to have some of the cylinder deck hole pipe plugged shut for forcing the coolant through the block then back up across the heads(convert to reverse flow cooling hint hint)have the engine decked only enough to square the head deck to the crank centerline(ensures proper cylinder to cylinder volume). select internal components that match your intended use then select pistons based upon good flame travel that complements the cylinder head chambers. a typical forged blower piston with a small dish positioned at .0005 below deck heigt with th stainless .045 head gasket and head studs. higher than normal placed top ring helps to keep the unburned hydrocarbons at bay due to slower/dirtier burn rates of pump gas, a gapless second ring and a low tension oil ring with a crankcase vacuum pump to control ring flutter to prevent ring breakage andexcessive oil consumptiongood rods such as lunati/oliver/carrillo is also key to LONGEVITY at this rpm level. 65 mph in third with a 4:10- is what 3800 rpms? (very tired bear with me almost dun). specifying a .010" ofset piston pin to the piston manufacturer is also a good method of reducing piston side loading. or going by the popular coatings route. maintaining 250-260 feet per second of air SPEED in and out of the engine at your projected torque peak is a must. i could go on and on but ive been up for 72 hrs now and i cant type any more. dont forget to remind the shop doing the machine work to balance the engine to match your intended rpm. port and radus all oil openings in the block along with bluprinting a stock h/v pump from a 409 w series "big"block (small block mounting big block internals and flow capacity with bigger pickup tube) oil control will need to be adressed. i havent even described cylinder head prep yet or even valve train. assembly and dissassembly will need to be done about 4 times, maybe more, before final assembly so be VERY patient all of the above us just to make sure the ebgine has reduced the ibternal pumping losses as best as possible. i've only given up a sample of the work that went into the engine we built the 7 p's apply here.

proper previous planning prevents **** poor PERFORMANCE!

good luck

and remember its just a simple 7500 rpm 302!

im not bashing im actually interested in helping!

later

chris

 

Almost gave me a headache reading that. You will not make up for 50 cubes no matter how you do anything. If you did all of the same above to a 350, it would make more power. Why bother? Also, we are comparing apples to oranges again. You are talking about more expensive heads and such.

That really doesnt resemble a 7500RPM redline 302 at all.

Reality check, the 302 will be beat by an equally prepped 350. or 327. or 400.

 

Does destroking a 350 cause the CR to go down? If so wouldnt that allow for massive amounts of boost? Boost would "make up" for that 50 cubes.

Or do I not understand a damn thing?

 

For the same chamber size between the two, the destroked engine will have less compression, but so what? Build an unstroked engine with lower compression and put the same amount of boost on it.

 

Why cut yourself out of the extra hp of the 50 cubes. Use bigger chambered heads and boost that. More HP, practically free at that point.