2 TBI's on an offenhouser crossram intake, on a 383 small block?.

Jason Zinn

Jason Zinn

New Member
Currently building a recreation of my fathers 1955 chevy gasser. He ran a 301 whith a crossram intake.
Planning on driving car on the street and an occasional jaunt down the track. i dont mind having an aggressive street car attitude. What i currently have, AFR #1100 completion port heads, and a 350 4 bolt block, o yea and the car. my question is has anyone played with dual Throttle body injection units on a crossram ? Opinions , Advise?. My Idea is a 383 AFR heads ,somewhere around 11-1 comp, stick shift , and whatever rear gear fits. I do not dislke carbs , just dont have much luck with them,also pump gas and current ratings on ethanol have me concerned ,and curious about wich induction system to use?
 
there Thousands of 1982-and 1984 cross fire corvettes were built with factory installed cross fire (CROSS RAM) intakes
with dual throttle body injection, so your hardly starting a new trend and ,
in the links posted here below,
theres of a good deal of info on related tuning

http://garage.grumpysperformance.com/index.php?threads/the-cross-ram-intake.623/#post-834

http://garage.grumpysperformance.co...sfire-vette-won-t-run-right.10096/#post-39710

http://garage.grumpysperformance.com/index.php?threads/a-few-cross-fire-tips.303/#post-936

http://garage.grumpysperformance.com/index.php?threads/crossfire-sleeper.12732/page-2#post-65554

http://garage.grumpysperformance.com/index.php?threads/ported-crossfire-383.10240/#post-41065

http://garage.grumpysperformance.com/index.php?threads/vintage-302-chevy.12071/page-9
 
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Hi Jason! Are you by the pretzel company? I'm a little over an hour from you as I travel through there frequently, your area has a better inventory on Craig's list.
Welcome.

Rich
 
Grumpy said:
there Thousands of 1982-and 1984 cross fire corvettes were built with factory installed cross fire (CROSS RAM) intakes
with dual throttle body injection, so your hardly starting a new trend and ,
in the links posted here below,
theres of a good deal of info on related tuning

http://garage.grumpysperformance.com/index.php?threads/the-cross-ram-intake.623/#post-834

http://garage.grumpysperformance.co...sfire-vette-won-t-run-right.10096/#post-39710

http://garage.grumpysperformance.com/index.php?threads/a-few-cross-fire-tips.303/#post-936

http://garage.grumpysperformance.com/index.php?threads/crossfire-sleeper.12732/page-2#post-65554

http://garage.grumpysperformance.com/index.php?threads/ported-crossfire-383.10240/#post-41065
Click to expand...
Thank you , looks like i have more homework to do
 
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you will certainly have a very functional performance induction system, once you get the systems idiocyncracys sorted,
Ive installed a couple of the offanhauser intakes with tbi injection over the last 30 years
the basic cross ram intake design has a lot going for it, its very compact and efficient.
where the chevy crossfire intake design fails is the port size runner length and the cylinder heads were all designed to maximize off idle torque with almost no concern for power potential once the rpm range exceeded 4000 rpm,
(exactly where the typical offanhauser cross ram intake just starts to shine in its power curve, with its much larger and more efficient intake design)
crossfire , (notice the much smaller runner size , less than 1/2 the cross sectional volume of the offy)
manifold7.jpg


OFFANHAUSER BELOW
ofy11.jpg

rencr.png

below the offy intake (below UPPER, the CROSSFIRE with its MUCH SMALLER RUNNERS LOWER)
crossports.jpg


http://garage.grumpysperformance.com/index.php?threads/the-cross-ram-intake.623/#post-53061

If you intend to build a SBC with a corvette cross fire engine as a starting point,
we certainly have a good deal of related info you can use.
we can sure help you make a lot fewer mistakes and help select good matched parts.

https://www.summitracing.com/parts/OFY-5893/

https://www.summitracing.com/parts/ofy-5903/overview/
 
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let us know what your planing and any progress on the engine build,
keep in mind that the newer self learning computer software available,
potentially makes the twin throttle body EFI on the cross ram a far more,
realistic and much easier to tune induction system, now than it was in the 1960s-90s


http://www.rodauthority.com/tech-st...ing-a-dual-quad-efi-system-on-a-65-belvedere/

http://www.efisystempro.com/efi-pro-hangout/building-twin-4bbl-throttle-body-engine



http://www.efisystempro.com/efi-pro-hangout/building-twin-4bbl-throttle-body-engine

http://fitechefi.com/products/30061/

http://www.superchevy.com/how-to/en...-into-the-latest-efi-systems-on-market-today/

http://www.hotrod.com/articles/car-crafts-giant-efi-test/

http://www.hotrod.com/articles/self-tuning-efi-systems/

http://www.enginelabs.com/news/entry-level-self-tuning-efi-showdown/

http://www.youngsperformance.com/

http://www.bgsoflex.com/megasquirt.html

http://members.ozemail.com.au/~davodos/Megasquirt.html

http://www.glensgarage.com/catalog/index.php

http://megatunix.sourceforge.net/

the MegaSquirt Forums http://www.msefi.com/
 
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I agree while this project sounds promising the idea of buffalo chicken pretzel bite sounds more promising and easier on the budget. Fitech has been coming along ways I feel there prices will be on the rise as there popularity is also on the rise and they are stepping into new territory.
 
PCE147.1087.jpg

the offenhauser 360 dual quad intake design was very similar in it design (to this intake above)
,in that it had a large common plenum and almost no individually runner length.
I had a couple of those, peak power was decent but mid rpm torque was down noticeably,
from the other dual plane dual quad intakes with longer individual runners, like the RPM air gap pictured below, but neither design can match a correctly designed tunnel ram manifold

$_57.JPG

a properly used tunnel ram, manifold is almost always the most effective , dual quad, or dual throttle body ,intake once the compression, is high enough and head flow potential will let the engine breath effectively to at least 6500 rpm, with a properly matched the cam, and that generally will have at least a 240 duration @.050 lift a fairly tight 106-110 LSA and a good set of matched tuned scavenging headers, with a long tuned collector, with a very low or no restriction exhaust

related links
http://garage.grumpysperformance.com/index.php?threads/semi-fool-proof-cam-sellection.82/

http://garage.grumpysperformance.com/index.php?threads/tuning-a-tunnel-ram-intake.5175/
216-large.jpg
 
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Jason Zinn said:
Yes,Snyder's Pretzel is about 10 minutes away,Glad to be on board.
Click to expand...
Sorry to break topic. My in-laws live not to far from the factory so every Xmas for nearly 20 years we get a case of Snyders Dark hard pretzels sent by UPS. The Harley-Davidson factory is close too isn't it? Since we're so close if you need any help just ask.
 
Grumpy said:
you will certainly have a very functional performance induction system, once you get the systems idiocyncracys sorted,
Ive installed a couple of the offanhauser intakes with tbi injection over the last 30 years
the basic cross ram intake design has a lot going for it, its very compact and efficient.
where the chevy crossfire intake design fails is the port size runner length and the cylinder heads were all designed to maximize off idle torque with almost no concern for power potential once the rpm range exceeded 4000 rpm,
(exactly where the typical offanhauser cross ram intake just starts to shine in its power curve, with its much larger and more efficient intake design)
crossfire , (notice the much smaller runner size , less than 1/2 the cross sectional volume of the offy)
manifold7.jpg


OFFANHAUSER BELOW
ofy11.jpg

rencr.png

below the offy intake (below UPPER, the CROSSFIRE with its MUCH SMALLER RUNNERS LOWER)
crossports.jpg


http://garage.grumpysperformance.com/index.php?threads/the-cross-ram-intake.623/#post-53061

If you intend to build a SBC with a corvette cross fire engine as a starting point,
we certainly have a good deal of related info you can use.
we can sure help you make a lot fewer mistakes and help select good matched parts.

https://www.summitracing.com/parts/OFY-5893/

https://www.summitracing.com/parts/ofy-5903/overview/
Click to expand...
I don’t mean to steal this thread but I’d love a ton of knowledge for helping my build. It’s a SJ 327 dated 1967 and I purchased a offy crossram w/ dual four top. I’d like to use Trickflow dhc heads. And the kicker Iam thinking of using fitech dual Efi set up or something else by your recommendations. Going to need to know what cam and should it be a roller? I want more street able use, it’ll never go on the strip.
 
tunnel ram, and cross ram intakes are designed to be effective in the upper rpm ranges,
cross rams tend to boost torque rather effectively once you hit about 3500 rpm,
provided the cylinder head flow, cam timing and compression match the intake flow potential
if the exhaust scavenging is also effective
use of efi helps fuel distribution issues but the intake flow characteristics,
are not ideal for rpms below about 3500rpm.
Id need to know your rear gear ratio, car weight,
transmission type, converter stall, and engine compression ratio
and several other factors before even starting to consider the cam that might work.

Ive worked on a bunch of the 1984 crossfire corvettes, and they benefit from a mild hydraulic roller cam
espectially if the drive train and gearing allows the engine to operate in what can be the engines ideal power/rpm band
and keep in mind most 1984 corvettes have the wrong gearing and very restrictive heads ,
and exhaust and a restrictive low compression ratio, and mild cam, in stock form,
all of these tend to restrict potential power.
give me a good deal more info , some idea as to budget , your experience,
and what your working with, as far as parts or restrictions etc. and we can work out a solution
BTW have you considered a 383 stroker KIT?
the increased displacement can do wonders,
but be aware some 327 blocks used a different size crank bearing size,
making the stroker crank kits , commonly sold not fit without extra machine work.

Crossfire sleeper

Kane, our poor CFI gets no love, lol
garage.grumpysperformance.com


lets say you can make 1.2hp and 1.25 ft lbs of torque,
per cubic inch of displacement
thus in theory


327=392hp/409 tq
383= 460hp/487 tq
 
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Factory 1967 rs camaro curb weight. I was hearing using the 2004r is a direct replacement to my PG. machine shop suggestions 10:1
 
knowing rear gear ratio and the converter stall speed also is important,
in the cam choice as is, the heads used, headers?
type of exhaust , pipe diameter ?
 
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67 rscamaro said:
I was hearing using the 2004r is a direct replacement to my PG.
Click to expand...
Did I hear someone mention the word 200-4R ???

Not sure about the powerglide, but it's the same overall length as a TH350 (short tail), but trans mount does change location.

TBucket 200-4R Transmission Project

Ok this is where I go, "Oh shit....what the hell was I thinking!!! Why didn't I just keep the THM-350 transmission that I had." Oh well it's too late for that now. The torque converter is here and the rest of my parts should be here next week. The torque converter has stall speed of 2800 RPM...
garage.grumpysperformance.com

GMTransDimensions.JPG
TransGearRatios.JPG
 
Grumpy said:
knowing rear gear ratio and the converter stall speed also is important,
in the cam choice as is, the heads used, headers?
type of exhaust , pipe diameter ?
Click to expand...
Yes headers, dual exhaust no crossover or H pipe, heads I would like to use Trickflow dhc heads, wouldn’t stall depend on cam selection?
 
Indycars said:
Did I hear someone mention the word 200-4R ???

Not sure about the powerglide, but it's the same overall length as a TH350 (short tail), but trans mount does change location.

TBucket 200-4R Transmission Project

Ok this is where I go, "Oh shit....what the hell was I thinking!!! Why didn't I just keep the THM-350 transmission that I had." Oh well it's too late for that now. The torque converter is here and the rest of my parts should be here next week. The torque converter has stall speed of 2800 RPM...
garage.grumpysperformance.com

View attachment 16123
View attachment 16124
Click to expand...
The 350 doesn’t have overdrive, which I’m looking for in the 200r4
 
Yes I'm aware. I love my 200-4R with the OD. I moved from the TH350 to the 200-4R
and didn't have to change the driveshaft, but I did have to change the mount. I'm
only taching 1900 RPM at 70 mph with a 3.70 rear end gear and 31 inch tall rear tire.
 
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