Belgian1979vette

Correct, only for ITB's the sizing is more critical due to the fact that there is no plenum to dampen the effect of the butterfly opening.

roscobbc

Cross Ram - something like this ?

http://www.kinsler.com/images/man_5.jpg

ylose

I think that is a side draft

TheSkunkWorks

There you go! ...tho that second one is a Weber setup. I'd go for side-draft IR injection in a hearbeat if I had the funds.


Belgian1979vette, agree, there's no plenum tuning with IR's.

roscobbc, sorry my PM box had gotten full (again). I'm far from qualified to conduct a class on such, but if you get me your head lift/flow ratings, cam specs, CR and header details (primary diameter and length, and collector diameter) I'd be happy to let you know what IR diameters and lengths my humble formulations spit out.

Belgian1979vette

Belgian1979vette

That second one is rather interesting.

roscobbc

Here we go Skunkworks - see what you can do here.

Heads are Brodix Race Rite Oval Port - 10.5 c/r - 2.25" intake/1.88" exhaust.
Lift .200".300".400".500".600".650".700"
Int 159 223 270 314 334 336 340
Exh 116 145 172 196 217 230 236

Cam is Howard flat tappet roller
Lift - intake .544" - gross duration 286 degrees @ .050" 234 degrees
Lift - exhaust .536" - gross duration 298 degrees @ .050" 240 degrees
Lobe Centre 112+4

Headers are currently Hedman 1 7/8" OD - changing to Hooker Super Comps - 2 1/8" OD - 30" length - 3.5" collector - will lead to 3" System with 'X' pipe and low restriction mufflers.

4 speed Muncie with 3.08 rear end.

Timing 22 degree initial - 38 degree total - all-in at 3000 rpm (I think)


Many thanks, Ross

TheSkunkWorks

Ross, I'll play around with it and let you know...

TheSkunkWorks

Keeping in mind the formulae I've put to use here are still a work in progress, and that the results yielded by these calculations are theoretically for max performance for the heads, cam, CID and headers in question, here's what I've come up with. (100% VE @ 29.921" HG assumed.)

HP potential of heads = 707 HP @ 6331 RPM
HP potential of heads with cam = 630 @ 6219 RPM

Peak torque w/100% exhaust efficiency @ 5671 RPM

Suggested IR throttle diameter @ 6219 RPM = 2.78"
Suggested IR throttle diameter @ 5671 RPM = 2.65"
Suggested IR runner length* @ 5671 RPM = 14.81"

*Staggered runner lengths (as per the Crower/McKay) may be required if heads have "good" and "bad" intake runners as are inherent to the BBC.

There's obviously room for more cam, but whether or not you should go there depends on what manners it needs to have. IMCO, if you want that cam to hang on a bit longer on top end, I'd consider installing it at 0-2* advanced. Again, I'd ultimately go by what an engineer recommends over the above. Hope that's at least interesting if worth nothing else.

carbster09

Shunk works,

I am with you! That side draft set up is way cool

If it would fit under my Big Block hood I think I would try to save the pennies for the set up for my 489! Pure sex!

carbster

roscobbc

Thanks for that - very interesting - so I guess a nice 'stout' roller cam should be also on shopping list to maximise intake flow improvements - thanks again for spending time on this

aaroncorvette

Nice works Skunkworks

Hey Ross, get the bigger cam he he, sorry to hijack

Anyone got any ideas on how to get some more power out of my motor without spending too much$ Say 30-50hp, i was thinking of swapping to a solid flat tappet cam

Here's my specs-

+30 350ci
Keith Black Hyper flat tops -6cc
Scat 2 rods
Lightened and balanced (revs up real quick)
Edelbrock RPM heads 70cc
Fel-pro head gaskets 0.015"
deck height 0.020
Edelbrock RPM cam
1.5 roller rockers
Air-gap manifold
Edelbrock 750vac sec
Aluminium flywheel
TKO 600RR 2.87 first, 3.55 rear

Approx 10/1 compression, DCR is a bit low though, the 70cc heads and ali flywheel don't help, i do have to slip the clutch a lot although it doesn't bother me that much

probably should have started my own thread

Any help is much appreciated, thanks.

gerry72

Interesting setup. Couple points to consider in this: injector positioning used for what we see on factory EFI port setups is primarily out of emission and packaging considerations. Power is a secondary consideration following emission certs.

Runners, if properly designed, account for wet or dry flow. This is why converting a dry flow manifold to wet flow does not work very well. No account was given for the space the atomized fuel will occupy. A dry flow maniflod also does not have to deal with fuel dropout, plating and puddling. Moving an injector upstream does have atomized fuel running in the same path as the air but we hope the designers accounted for this in the application engineering.

The space atomized fuel occupies is tiny compared to the space vaporized fuel occupies. We'd like vaporization to occur primarily in the combustion chamber and in most cases, it does work that way. The heat of compressing the mixture is primarily what contributes to vaporization. You need really large runners or boost if you want vaporization to occur in the intake tract. This would be a vapor cycle engine.

Moving the injector upstream does allow for better fuel atomization to occur and the better your atomization, the easier and more thorough the fuel turns to a vapor state in the cylinder and fuel will burn only in a vapor state since that is the only way it can mix with air. The factory addresses this less than optimal injector placement with velocity and swirl. It works quite well.

roscobbc

Cam chosen was a relatively low lift owing to flow rates of head - couldn't see too much point 'lifting' valves higher than point where maximum flow rate in heads occur. A cam with more aggressive opening and closing ramps was selected to keep valves effectively open longer and give a usable power spread from 1500 to 6200 rpm. Replacement of hyd cam to roller cam will need to be more of the same I guess (agree/disagree?) Guy who built the engine suggested that there was another 70/80 hp available with a roller cam. I am really interested Skunkworks on seeing your figures worked back and seeing where A a 2 3/8" diameter 12"/13" high Kinsler type runner and B a low riser 2" diameter IDF/IFA throttle-body would produce power/torque etc. ( bearing in mind that this is for a street driver car) Thanks again, Ross

Dr L-88

What kind of induction system is this and is it readily available?

TheSkunkWorks

The calculations for projecting the heads' potential HP are based strictly on max flow rating when installed on a 489 CID V8, and by extrapolating flow at the cam's max lift from those ratings. As there are a number of other significant factors which affect output in the real world not accounted for in such models (I haven't "built" it in EAPro as of yet), these calculations are meant only as a reference point much in the same way as are theoretical DCR models. That said, it's interesting that the 67 HP difference between those HP potential models is pretty close to the 70-80 HP the engine builder estimates that might be had, so I'd say we're in agreement there.

The peak torque RPM projected was based strictly on 2 1/8" x 30" x 3.5" headers installed on a 4.25" x 4.28" V8 at 100% header efficiency, and the IR runner length was extrapolated to match that resulting RPM. You can see where there's plenty of room for error, especially as I have not accounted for muffler restriction or any other limiting factor which would tend to lower peak torque RPM. That said, shorter runners will tend to pivot the torque curve about the peak towards higher RPM.

Regarding the 2 3/8" IR throttle diameters, is that wet or dry? My calcs for IR throttle diameter are wet, as they calculate for the total CFM of A/F mix which flows into the cylinder. FWIW, dry, I come up with the 2.375" IR throttles as being optimal for peak torque at 4917 RPM, with 2.55" diameter matching up with the bigger headers. I show that dry 2" IR's would "tune in" at ~3500 RPM.

In any event, keep in mind that while intake and exhaust tuning are important, variances between the two are common when buying off the rack, and that observed torque/power curves don't always follow theory.

And, again, there being plenty of room in my maths for tweaking , I caution anyone taking these calculations as worth anything more than entertainment. An engineer I ain't, so if anyone with a better grasp on this stuff wishes to chime in, by all means do so.

Belgian1979vette

Yes, DC & O in Australia makes them. Not cheap, but cheaper than anything other that i saw and well made. It's basically a Weber side draft system without carbs, but with injectors. 8 throttle bodies, 1 per cylinder. I paid € 2000,00 for the entire set if i remember right, but make no mistake, this is absolutly not the intire system, you still need plumbing, fuel pumps, injectors, wiring,................................. .......$$$$$$$$$$$$$. Tuning is also not easy.

As far as skunks calculations : a word of caution : these systems usually work with the smallest size you can get the intended horsepower. Overengineering can cause drivability and tuning issues.

roscobbc

Interesting products - unfortunately (for me) BBC units are rectangular ports.

TheSkunkWorks

...and I have no problem with that observation.

Belgian1979vette

Did you check them ?

This is a link to a BB unit. Price seems high, i think you can get it cheaper if you contact DC & O directly. Should have the info here somewhere. At the time i ordered they were best contacted by fax. The guy is pretty old and not into emails and stuff.

http://stackinjection.com.au/main-gr...qp9nl7e3r8cul7