** Video on post #167 **

My next project will be a single plane efi intake,
There has been some interest on here recently about them, I have been following Bogor's thread in Forced induction although his build is based on a turbo set up and Agenteran has asked the question here.

My plan is to build something similiar to what rcklessdriver has, use a single plane efi manifold, custom make an elbow/plenum and use the L98 throttle body / air intake / throttle cables and sensors and wiring. I dont want to spend a million dollars on it, just build something that will work better than the TPI. I recently had to pull the TPI off and on 3 times lately and consequently have grown to hate it ! Also having a 383 setup I know the TPI is leaving rpm and horsepower on the table.

I have done some research, mainly on thirdgen as they have several threads on single plane intakes.

I have chosen the Procomp intake as the base, and before the pro-american chanting begins, I live in Australia and they are the only company selling efi intakes here, they might be made in china but they do use Australian raw product (steel and alloy) so I can sleep well at night after making this decision

To back up the decision of performance, this test by Carcraft tested 19 single plane manifolds, the procomp Hurricane finished 7th in horsepower, 7th in torque and 7th in torque/per $ cost.
http://www.carcraft.com/techarticles...t/viewall.html
I know they were carb setup but it shows they do perform and there were no issues with fitment etc.

It was interesting to read stuff on other forums re the procomp stuff (also sold as the Professional Products efi manifold), "Ive heard they are rubbish" "I have heard they dont fit properly" surprisingly none of the people making those comments have actually ever used one ! the people that have admit that they fit and work well, with some doing there best 1/4 mile times with the Hurricane after removing Edelbrock and Accel manifolds. One showed a photo comparison of the Edelbrock v Hurricane, the Edelbrock required much more work to gasket match, the Hurricane being 1205 ready out of the box.
When its all said and done I have the manifold now and it looks ok so far, a couple of threads might need cleaning up, a couple of pics below,





Any advice or questions on this build would be gratefully accepted, especially from those who have done it before.

 

I have been toying around with this idea for a while now. I am currently running a Stealth Ram and '165 ECM on my 385. To make it easier I would have to switch to MAP and that would add to the cost.
It still interests me, so please keep us updated.

 

there WAS a project that did exactly this a year or two ago....took a similar manifold and made the bolt-on top that was an elbow to a block that mated with the stock style TB...it was little in the plenum dept but mucho in the simplicity area...the results were good initially but I don't recall the full butt-dyno accounting of the benefits and/or losses. I can't tell ya the thread title or even where to search that. Someone DID do this though...its been a while.

There was a different "experiment" where a ls or lsx style intake was used as a model, with short runners that were made off the head, then a box made inside or under the runners so they wrapped around and the entire underside of the runner was the plenum...so each runner was acting as a portion of the plenum when they were all combined.
I guess the obvious goal is to make short runners for enhanced top end breathing and to shorten the pulse/wave cycles of intake cycling, and yet maintain a high enough vol of fresh, metered air so the vac never got too high starving the motor the faster it went. The key to success is to keep as much of the "blow-gun" effect that helps low end and mid-range, but make the upper rpm range as efficient as possible so the motor didn't run out of breath. Blow gun as in the high velocity of high vac when that vac is suddenly relieved, like when the intake valve suddenly opens. THATS low end in a naturally aspirated engine. BUT, thats also the exact opposite of how to get TOP end performance...rob pete to pay paulie...
There is a balance to be found somewhere in the successful design...

If you do some googling there are formulas out there for plenum and runner design that teach what you need to do, but the design/shape is totally up to you....take the ford rustang HP intakes that have all runners side by side and the TB opposite the middle 2 runners. This LOOKS like crap, but it works quite well ! Other similar designs have the TB at the end of the row of runners. It seems like the farthest runners would have to have a different vac level and therefore a different output, but they don't. The plenum vol is capable of supplying enough metered air to satisfy them all without any single runner starving....somehow.
The BIG problem with the C4 experiments is that we are bound by Height....which limits that portion of any design.
The secret has to be runner length, plenum vol and how to manipulate the vac to assist the low end while making top end free-flowing....ya want high vac at low end (to simulate long runners) but not after 3000 or so rpm, so you can have the 'breath' to pull hard to 6000...the intakes design is how that's got to be accomplished. Quite the challenge.

Wish I had a pile of aluminum and a nice TIG rig...I'd be building experiments daily. The one time that I DID design something thru what I learned online, it came out to strongly resemble the lingenfelter design...a much wider plenum that sat on top of shorter runners that went straight up to meet the underside of the plenum...
Makes ME wonder if the easy designs are already in production?
I also wanted to play with variable runner size/volumes to see if that was an area where the runner length could be compensated for, to find the right 'flow' for good low end and have good top end as well...best of both worlds.
We saw a LOT of performance 2 stroke engines with "reeds" back in the day....I always wondered IF reed-valves inside an intake might benefit a rough cam profile by preventing the backflow of intake air, but allowing big flow on the intake stroke...?

That's why they sell lottery tickets. Most folks would go buy a house and take a vacation. I'd buy a machine shop.

 

I did grab a TIG last year to learn on, but DC, so not aluminum friendly. I think Aardwolf is running a single plane with the elbow and LS throttle body. He is also running an L88 scoop (like myself) and has the elbow pointing rearward toward the windshield. His build is what piqued my interest in the layout.

I agree completely. A huge garage/workshop and the machines to fill it are definitely on my lottery wish list.

 

That intake may be pro comp.. but it looks great!

I too have been studying the thirdgen posts on the single plane subject.. It seems like you would see more single plane efi set ups by now.. the examples that do exist seem to work well..

Looking forward to updates!

 

 

Leesvet raises some good points,
the setup is constrained by issues such as hood height, manifold design, what throttle body and intake piping is to be used etc,
this is the type of intake elbow I will be making, the consensus of opinion is that a smooth flowing wall is better than flat walls (i.e. a tpi style plenum)



the one draw back with this style is that the air will flow to the rear of the elbow causing rich cylinders at the front and lean at the back, it needs a divider inside ,



It has been stated that the plenum should be between 50 and 75% of engine capacity and that automatics need less plenum than manuals, you would need to measure the intake elbow area and I would suspect the plenum area of the intake manifold would count too ?

 

Bearing in mind that the intake you are using is documented as 1.5 " taller ( 6.05 " ) than the more commonly used ones like a Victor E (4.58 " )

 

..... It has been my experience that single plane intakes dramatically change the power band by moving it upwards on the RPM scale ... especially when changing from a TPI ... you WILL lose that bottom end torque ... the whole build has to be altered now to compensate ... not that that is a bad thing ... I would never go back to a TPI ... two major items to consider are gearing and a high stall torque converter ... assuming the engine build itself is already directed at the power band level forced by the SP intake .....
..... The real challenge is to come up with an intake that has some length , cross sectional area , and taper in the runners to take advantage of the "waves" that produce the ram effect that makes the power that you seek ..... Do some research on the FAST 102mm LS7 intake and you'll get a better idea of what I'm talking about ... AND take an analytical look at Lingenfelter/Accel Super Ram ... and the Holley Stealth Ram (which would be much improved with a larger opening at the upper end of the runners) ..... the end result needs to reflect the REAL usage of your car ............
..... Stay tuned , because the mad man in me is still trying to find/fabricate a better mouse manifold ... and I may be onto something.......

 

The Hurricane is a great intake for the $$$.

I ran one on the 427 SBC in my 84 and went 9.30's@148mph with it unported OTB.

It is tall compared to most other intakes. 5.8" to the carb flange. That will be tough to fit under a stock C4 Corvette hood... On my 84 which is carburated... a QFT Q-950 carb came dead even with the bottom of the hood... I cut a hole in the hood and used the hood as the bottom of an air pan for a small forward facing hood scoop I had on the car until I cut it all out and installed the big cowl induction scoop it has now.

The Super Victor 2925 I have converted to EFI on my 92 is only 5.50" to the carb flange.

The taller intake is going to limit how tall and how good of a radius you can put on your elbow/TB adpater.... Ideally you would want it to be as tall and as gentel as possible....

My elbow/TB adpater on the 92 worked out to be only 3.5" tall to fit under the stock hood. I was lucky in that I had someone help me with my stuff that had already done it. I was able to take what he had done and tweek it to what I have on the car today.

A 90* elbow for the TB adapter works fine.

You do not need or want a divider in the elbow of a Normally Aspriated engine. The dividers are to help air distribution on Forced Induction engines with tight radius elbows.

The engine in my 92 was designed to be a 7000 RPM deal but it makes good power everywhere. The engine has an awesome TQ band from 3500 to 6000RPM.... dead flat 400RWTQ... it still has over 300RWTQ at 2500RPM so it's not like it's hurting for power down low.

3350LBS daily driver with working AC and all creature comforts. Other than a good clutch and rear gear the rest of the car is just an ordinary 92 Corvette. It's been 128mph in the 1/4 mile normally aspriated on 93 octane pump gas.

The right single plane intake is a great package.

BTW I recently convinced a C4 Corvette road racer on this board to buy a Holley 300-25and install it on his car.... His engine carburated but limited to 5800RPM max because of the stock crank, rods and hyper pistons.... 38RWHP and 40RWTQ across the board gains. It didn't loose any TQ anywhere and most people would tell you that putting a serious racing single plane intake like the 300-25 would have killed his engine...

Will

 

Looking forward to follow your build

 

some great info and suggestions, its good to hear from people who have done it,
the consistent thing is everyone saying "watch your clearance" , I was aware of that and measured the TPI when it was last off, to get the china wall to plenum heights (front and rear of the plenum) and then did the playdough check,



I now know how much room i have in my engine bay under the hood,



I have 9 1/4" at the front of the plenum and 11 1/2" at the rear, so Im figuring on using 9" at the front and 11" at the rear, I was surprised how much room there was, if you look under the hood there is a big hollow along the centre of the hood from front to rear that clears the intake from the radiator back to the distributor.

 

Yep 9.25" from the china rail to the hood where the intake manifolds TB flange is....

Keep in mind the hood slopes downward from there so its shorter out past the TB.... pay attention to how much angle you put on that TB flange....
Will

 

..... Check this out if you have a few minutes ..........

http://forums.corvetteforum.com/c4-t...ght=sneak+peek

 

I like this and wouldn't mind trying it out some day on a car, but who knows if I'll ever get around to it. Also be nice too use with maybe a newer ecm and LS TB. Vortech Igloo

base


top

 

Thanks c409, I have read that thread a couple of times, the one thing i took notice off is the problems with the bottom of the IAC housing hitting the top of the thermostat housing, the advantage of fabricating your own elbow is that you can put the throttle body where you want, Im thinking of mounting the TB with the IAC housing just short of the thermostat housing (it only needs to miss it by a poofteenth of an inch ).

 

Ive just realised that i need to take a playdough measurement half way along the plenum, thats the point where the elbow will actually come up towards the hood,
I figure if the TB mount is in line with the "natural slope" downwards from rear to front (ie from 11" to 9") it will be ok ?

 

that looks a bit weird, surely there must be a base under that base ?

 

Your seeing the bottom of the base it has the 4150 flange too mate with a single plane intake.

 

Argh, i see, its upside down ! I knew it had to bolt to something.