BOTH the OFFY and the SY1 were DESIGNED for producing max power in the 3500rpm -7000rpm plus band in the 302 displacement SBC, used in the ORIGINAL TRANS AM RACE CARS, they work great on the larger SBC PROVIDED the cam, compression ratio, and CYLINDER HEAD FLOW RATES and gearing keep the engine in its effective operational band which stays at or about 3000rpm- 7000rpm due to the design of the runners length,and cross sectional area.
since they are basically max effort race intake designs no effort was made to make the under 3000rpm performance work very well, and you'll notice that if you install either intake, yet above about 3000-3500rpm with a 383, with 10.5:1-11:1 cpr and the cams listed below they come alive once the rpms build...if you've got the manual trans and correct rear gearing to keep the rpm band in the 3000rpm-7000rpm band.
BTW its kind of a waste to install a HYDRAULIC cam as most hydraulic cams enter valve control issues in the 6000rpm range,area, where the intakes pull very effectively, so you'll want a solid lifter design that can reach 6500rpm plus to 7000rpm, too maximize the intakes potential, OR too install these intakes on heads that flow less than about 250 cfm at .500 lift as that would restrict the intakes flow potential.
both can support 450-500HP as they flow 270 cfm plus (UN PORTED)while the stock cross fire flows less than 190cfm,the difference in power is simply amazing IF you match the components correctly so ALL the components maximize that 3500rpm-7000rpm power band.
NOTICE the stock cross fire restricts power badly above about 4000rpm with its 190cfm flow,so they are totally different types of intakes even thou their design looks similar.
if you use a basic 383 engine size they produce even better power.
Ive found the cam that works best for street/strip use in a hot street car combo is usually the 114681 or 110921 CRANE solid lifter cams and a 4.11-4.56 rear gear ratio and a manual trans.
now Id point out that they both can be a P.I.T.A. to tune if your not good with carbs and the offy is designed for two small four barrel carbs, in the 450cfm-600cfm range, the SY1 for a single 780-850 cfm
YOU can ADAPT the bases to use the STOCK or modified TBI injection off the cross fire, but it requires an adapter plate to match the base,
theres a guy on this site than makes the correct adapter plates.
http://www.crossfire.homeip.net/
http://www.exeterautosupply.com/Docs/Of ... atalog.pdf
BTW the SY1 doesn,t hit the windshield wiper motor while the OFFY does, and both will require a small dia. distrib. the OFFY is still easy to buy off summit racing, the SY1 is only available USED
http://store.summitracing.com/partdetail.asp?autofilter=1&part=OFY-5893&N=700+115&autoview=sku
http://coloradohotrodparts.com/Offenhau ... Y-5901.htm
BRAND NEW LOWER WITH GASKET $344
http://store.summitracing.com/partdetail.asp?part=OFY-5903
dual quad lid $150 NEW
BRAND NEW LINKAGE $117
http://store.summitracing.com/partdetail.asp?part=OFY-5902
this link gives you good info
http://jobyteknik.homeip.net/corvette/2002-11_offy_installation/
BTW Ive used BOTH intakes with CARBS several times ,on my cars and would not hesitate to do so again,and they look and run great once tuned correctly, with a conversion to TBI it easily something you can do, but it takes more work and while Ive worked on a couple cars that were modified that way, its not as easy as carbs, too use and tune, so while its a huge potential increase over the crossfire, the TBI, will require a bit more effort
IF you want to maximize the results, you can produce using a cross ram intake, youll need to have a set of heads and a cam ETC. that match the full flow potential of a mildly ported cross ram intake and its designed power band, which is in the 4500 rpm 7000 range with a 377-406 sbc which most guys will run if theres no limits on displacement, it will result in a combo you can,t run on street octane fuel, (PUMP GAS)
but it will produce a good deal more hp.
the changes will require you to swap to heads like
the 210cc AFR,
http://www.airflowresearch.com/index.php?cPath=24_33
or 210cc profiler heads
http://www.profilerperformance.com/sbc-heads-176.html
two 600cfm holleys
a solid roller cam similar to this
http://www.cranecams.com/?show=browsePa ... e=camshaft
and about 11.5:1-12:1 compression
Id strongly suggest a FORGED internally balanced rotating assembly with 7/16" ARP ROD BOLTS
a manual transmission and a 3.90-4.11:1 rear gear range is the absolutely lowest numerical ratio, range Id consider ,on short tracks, with 4.56_4.88:1 being a better match on short tracks
keep in mind youll want to keep that combo spinning in the 4500rpm-7000rpm band, and that requires roller rockers, a rocker stud girdle or shaft rockers and a well designed 7-8 quart oil pan and windage screen to maintain oil pressure
full length headers designed to match the cam profile selected, and open headers with a tuned collector
http://www.scatcrankshafts.com/ (310-370-5501)
CHEVY 400 SMALL-BLOCK 2-PC REAR SEAL 400 MAIN, 4340 FORGED CRANK, I-BEAM OR H-BEAM RODS WITH 7/16" CAP SCREWS
CI Crank Rod Piston Boresize Type 58cc 64cc 70cc Inclcrp Inclcrprb Compl
377 4-400-3500-6000 2-350-6000-2100 PREMIUM FORGED 4.155 FLAT 11.6 10.8 10.1 1-41010-1 1-41010 1-41010BI
377 4-400-3500-6000 2-350-6000-2100 PREMIUM FORGED 4.155 DOME 14.2 13.0 12.0 1-41210-1 1-41210 1-41210BI
407 4-400-3750-5700 2-ICR5700-7/16 HYPEREUTECTIC 4.155 FLAT 12.5 11.6 10.8 1-41250-1 1-41250 1-41250BI
407 4-400-3750-5700 2-ICR5700-7/16 FORGED 4.155 FLAT 12.5 11.6 10.8 1-41255-1 1-41255 1-41255BI
407 4-400-3750-5700 2-350-5700-2100 PREMIUM FORGED 4.155 FLAT 12.5 11.6 10.8 1-41260-1 1-41260 1-41260BI
407 4-400-3750-5700 2-ICR5700-7/16 FORGED 4.155 DISH 10.4 9.8 9.2 1-41305-1 1-41305 1-41305BI
407 4-400-3750-5700 2-350-5700-2100 PREMIUM FORGED 4.155 DISH 10.4 9.8 9.2 1-41310-1 1-41310 1-41310BI
407 4-400-3750-5700 2-ICR5700-7/16 FORGED 4.155 DOME 14.0 12.9 11.9 1-41355-1 1-41355 1-41355BI
407 4-400-3750-5700 2-350-5700-2100 PREMIUM FORGED 4.155 DOME 14.0 12.9 11.9 1-41360-1 1-41360 1-41360BI
407 4-400-3750-6000 2-ICR6000-7/16 HYPEREUTECTIC 4.155 FLAT 12.4 11.6 10.8 1-41400-1 1-41400 1-41400BI
407 4-400-3750-6000 2-ICR6000-7/16 FORGED 4.155 FLAT 12.4 11.6 10.8 1-41405-1 1-41405 1-41405BI
407 4-400-3750-6000 2-350-6000-2100 PREMIUM FORGED 4.155 FLAT 12.4 11.6 10.8 1-41410-1 1-41410 1-41410BI
407 4-400-3750-6000 2-ICR6000-7/16 HYPEREUTECTIC 4.155 DISH 11.1 10.3 9.7 1-41450-1 1-41450 1-41450BI
407 4-400-3750-6000 2-ICR6000-7/16 FORGED 4.155 DISH 11.1 10.3 9.7 1-41455-1 1-41455 1-41455BI
407 4-400-3750-6000 2-350-6000-2100 PREMIUM FORGED 4.155 DISH 11.1 10.3 9.7 1-41460-1 1-41460 1-41460BI
407 4-400-3750-6000 2-ICR6000-7/16 HYPEREUTECTIC 4.155 DOME 14.2 13.0 12.0 1-41500-1 1-41500 1-41500BI
407 4-400-3750-6000 2-ICR6000-7/16 FORGED 4.155 DOME 14.2 13.0 12.0 1-41505-1 1-41505 1-41505BI
407 4-400-3750-6000 2-350-6000-2100 PREMIUM FORGED 4.155 DOME 14.2 13.0 12.0 1-41560-1 1-41560 1-41560BI
434 4-400-4000-6000 2-350-6000-2100S PREMIUM FORGED 4.155 FLAT 13.1 12.2 12.2 1-41565-1 1-41565 1-41565BI
434 4-400-4000-6000 2-350-6000-2100S PREMIUM FORGED 4.155 DOME 14.6 13.5 11.6 1-41566-1 1-41566 1-41566BI