Who Makes the 4 bbl intakes that work on L-6s

[ozconnection]

Do you think it was a deficiency in the carbs that you were using or the design of the manifold that was causing the top end power loss?

 

How much time did you guys spend attempting to optimize those carbs?

 

I have a 4 barrel throttle body with 4 injectors that I was seriously thinking of running (on either manifold) to improve on one variable if it was deemed the carby to be the biggest problem area?!.

 

Are you sure you cant have a little look around for some dyno sheets or pictures for all of us (me in particular) to see please?

 

Cheers.

[Tony D]

The Manifold Vacuum with the Predator was such that it was indicating airflow restriction downstream of the carburettor. The VV in the thing was nowhere near where it 'should' have been even with custom camming of the mechanisim. Fueling was adequate, but the VV mechanisim was not opening further as it should with an engine flowing that kind of air. We spent a fair ammount of time with both a larger holley and the predator. We got slightly more out of the Predator than we did out of the Holley, but in the end it was only about 215 at the rear wheels.

When you compare that to almost 100 more with the same cam, head, block, piston, etc....but at almost 8500 rpms instead of 7000.

 

I can't recall the exact datalogs but with the TWM induction setup we are running something like 95 or 98 KPA at WOT and peak HP (forget which), whereas with the Carbs the manifold vacuum signal was nearer several inches of mercury. The Webers moved our power peak up 500 rpms to 7500 instead of 7000. With the other manifolds and 'more than enough carb' the carb flow was there to accomodate that kind of rpm, but we never got the vacuum signal at the carb to allow that metering to take place. The main problem we had with the carbs was that they need restriction to work, while our engine wanted and liked less restrictive flows on the inlet side. Maybe with an EFI Air Door the results would be different---that may be something you can tell us. But again it depends on the use of the engine as well. Power at 7500 or 8500 is probably not an issue on the street.

 

Does that make sense? The Holley gave good results, but with a 650 we figured to try the Predator since it was supposed to flow more. When the VV Predator got on there, it ran stronger to be sure, but it just started getting sluggish above 6500. I posted some dyno sheets long ago, but I wouldn't even know where to find them other than to say generic ZCar.com...and then someone else was hosting the images.

 

The idle signal was a problem for idling as well. The Holley idled around 2000 rpms for proper smooth operation. The Predator 2200. The Weber 45's 1700. Down low the plenum wasn't happy with our overlap and vacuum signal. I think the datalog shows us idling now around 58-65 kpa.

 

Besides, I'm in Spain now, getting ready for a flight to Morocco, and then on to Nigeria...so I couldn't find those dyno sheets even if I did know where my wife relocated all my files to! >:^(

 

The dyno curves look similar to yours anyway, just with a peak closer to 62-6500 and tapering off slightly faster. I want to say 213 with the Holley, 217 with the Predator, 237 with the 45 DCOE's, and 256 or 286 initially with the TWM 45 ITB'sand TECII.

 

With the Webers the power fell off quickly past power peak, even at 7500. We were loath to run to 77 or 7800 for fear of loosing acceleration time. The Predator was kind of 'flat' from 6500 on, similar to your graph. When you compared the Webers to the Predator, the jump of 20hp was at 7500 rpms, over where the Predator was at that point of the rpm curve. At the Predator power peak of nearer 6500 rpms, the power difference was more like 7hp difference, but it kept pulling towards higher rpms. That made for us being able to pull between gearspreads better. When we went to the TWM setup, the difference at 7500 was more like 17 hp, but that more than doubled by the time you hit 8300 rpms compared to the Webers (close to 40HP more at that point!)

 

Curiously, the same cam in our 2-Liter has a hellacious output dip at 5K rpms now...but pulls like gangbusters over that point...to over 9500 rpms. Different engine, different characteristics. I always found that interesting.

[ozconnection]

Thanks Tony for your insight.

 

I'm curious how you managed to get a predator carb under your bonnet line with some sort of air cleaner attached?

 

I guess its probably a combination of low air speed in the Cliffords plenum along with the induction pulse 'soup' that's created that can either enhance or detract from performance. I also found a large degree of idle insensitivity on my holley ie a weak signal. I did manage to overcome this somewhat with a combination of altered low speed air bleeds and a shortened transition slot(s) for off idle tractability. As far as the rest of the induction system is concerned, I'm reasonably confident that there is an optimal port and cam profile combination that'll work very well. I doubt if anyone is motivated enough to try though, you and I included. Shame.

 

I may decide to try the 4 barrel throttle body on my car to see how much it improves drivablility. But it would be a fairly expensive upgrade to a fairly sedate 'daily driver' even though it doesn't serve as one anymore. I bought it to use as a blow through setup on my 240C coupe that's being built as we speak. I have thought about buying an engine management computer that has the ability of storing multiple maps. I could use one map for the 330 and another one or two for the 230, the logic is that I can't drive both cars at once but I would need two 4 barrel throttle bodies. Buggar. A good security device though.

 

I found that when I had the L20A in my car whilst the L28 was being rebuilt, I kept the turbo cam in it. It was a factory L20A ET engine. I ran it in N/A form at that time. The thing would buzz easily to 7.5k rpm with a very linear power delivery. When I put the L28 back into the 330, I decided to give the L20A cam a try. WOW, what a difference. A completely different car to drive, lots of torque down low, excellent if fact, but it hit a brick wall at anything above 4.5K rpm. Compression ratio, rod ratio, port and valve size etc aside, I guess the point I'm making is that you don't always know what to expect from a new combo until you give it a try. :burnout:All I need to do now is to take my own advice!!

 

Cheers.

[Tony D]

I'm curious how you managed to get a predator carb under your bonnet line with some sort of air cleaner attached?

 

 

We didn't! It stuck through the hood and had a large scoop facing forward in the slipstream over the hood. Andy commented that over 130 the car actually seemed to be pulling much harder through that relative rpm band than it seemed to on the dyno.

 

I guess that's where we got the idea that there was a restriction somewhere downstream of the VV setup of the Predator. RElative Cam position (as revealed by wipers on some bluing applied as a tattletail) indicated that the venturi was opened more under load on the lake than it did on the dyno. Normally that would mean it had a higher vacuum signal in the manifold to open the venturi up some more (all readings at WOT).

 

The way I could best describe the engine with the four barrel manifold on it was like an old Capri with the German V6 in it and the US spec Two Barrel. Engine pulled well to 4500 in that case, but simply would not any faster. Many Ford Fans swore there was a rev limiter on the engine. But put the Eurospec IDF or a Rochester 500cfm 2G on it and the same engine would twist the tach around to bury it. Totally intake restricted. Well, we put the predator on there, and it should have been the 'IDF' for the Datsun...it was more than enough flow, and supported a 500CID engine at 6500 rpms quite well. But we just couldn't get it to open up and rev well above 6500-7000. Put the Webers on it and ZING to 7500. TWM's ZING to 8500,9500+!!!

 

It should have done that with the flow capability of the Predator. We lightened all the springs and cams to let it open up and allow max flow, but it never did. I mean it's a 950cfm carb for gawds sake...it 'should' have been enough. We were running it on only 176 CID...which explained why it would idle at 2200, over 2X what the 502 ran it at for idle speed. AFM was good all the way up, it wasn't going rich on the top end or anything to limit flow. WE actually tweaked it a bit richer than the dyno pulls from what we saw on our AFR meter on the dash during the run, and that's when Andy commented on the picking up acceleration at the top end. It's what kind of sold me on running Mustang-Style Load Bearing Dynos over inertials. When you only get one run (maybe two) in a month, your car needs to be right as it drives OFF the dyno, not adjusting for radical mixture changes (outside of normal density checks) just to get it to pull correctly on the top end. I think the 45's had a theoretical flow capability of soemthing like 1100cfm if memory serves. For the difference in the way it pulled, it wasn't 'small' like the difference between the 650 Holley and the 950 Predator. It was a BIG bump and increase in RPM capability of maybe 500-1000 rpms. I don't know if we could have even kept the engine running using an 1050 Dominator on the thing, and for the costs involved it was Cheaper to go with the Webers which were a 'borrowed from Dave' situation. When we maxed out the 45's, the Dyno Operator was suggesting 55 Webers for our next step in power, and the costs for the manifold and carbs were comparable with the TWM setup (around $4K USD at the time, plus EFI system, plus Tuning...) But ultimately the EFI gave us rock solid consistency, the ability to turn the key and have the engine fire up and idle while warming up at a speed relatively low (hell we could idle the ITB's to 400rpm!!! Threshold of the 'cranking limit' on the TEC.) and all on a 39F November Morning.

 

Such was not the case the previous November with the Webers, or previous Novembers with the Predator!

 

Ultimately, the car went 143.325 mph at El Mirage with the Predator on it. The Webers got to the 150's, and TWM went into the low 160's, with mid 170's at Bonneville. I think the 2000 SCTA Rule Book has a picture of our car on the cover with that predator sticking through the hood and a 'cosmetic' scoop we stuck on it for most of the photos (hey, it was chromed!)

 

Putting it all in once place like that, I can see now we made X HP with 650cfm, X+ with 950 CFM, X++ with 1100CFM, and ultimately X+++ with our final 45mm ITB setup (forget the cfm of that potential, but I know it's measured at a different manifold depresison than carbs...they pump air easier as they need no restriction to work! So maybe no restriction on the front end of the Four BBL Manifold would work well. 1100CFM air doors are plentiful on E-Bay... But we sold ours long ago.)

[ozconnection]

I guess when your motoring along at 130+ mph, you could afford to try your luck with a little 'free' supercharging (Ram air tuning!). Great idea you guys had and one very few of us will ever get to worry about! It made sense when you said Andy richened the mixtures and the thing went harder at the top end. You'd never see this happen on the dyno and for obvious reasons.

 

My searching around for 4 barrel intakes for the L Series came across the E32. A factory 4 barrel intake manifold and one very similar to the 'candelabra' two barrel manifolds (E30 and later P30's) found on 1970's Cedrics and probably some others. Rumour has it was used on an S30, but I can't prove or deny this. I do like the almost complete separation of this design and have often thought that if the manifold was built with 35mm runners instead of the P30's 32mm or the E30's 30mm ones, it might go a long way to minimizing charge robbing, especially compared to the Cliffords 1/2 and 5/6 cylinder runner configurations. The bends on the Nissan runners have a generous radius unlike the Cliffords runners.

 

I have looked at the Offenhausers dual port offerings for the L4 engines. Why didn't they make one for the L6??? Doesn't make any sense to me at all. I do like the theory behind these manifolds and how good they'd be for street engines where superior low speed torque would be complimented by great top end power. Your thoughts?

 

Now if you could blend these two ideas together, then you'd have a very good 4 barrel manifold IMO. There is probably something fundamental that I've overlooked but on the surface I like it.

 

There is nothing like the consistancy offered by fuel injection. I hear you Tony. That's the reason I bought that throttle body. At 1000 cfm flow potential and without the restrictions imposed by venturis, I might get lucky with this one.

 

Cheers

[Tony D]

Where is that E32 manifold? I have NEVER seen that one before. If it's complete with the accompanying carburetor (even if the carb is shot) send me a PM...and throw in a price. I'd be willing to spend some $$$ to get that thing statesite and stick it on a car (er...I'm thinking early 810...) and watch people scratch their heads.

 

It is similar in the radius to what I recall the Mercedes units with, and the separate runners in the manifold make sense to keep velocity up on the smaller barrels while running around town with the secondaries not engaged. Then when you open it up, you get the full flow of the setup through both runners---keeping velocity high on the small primaries and insuring the secondaries don't open till sufficient draw is there for the secondaries to give adequate velocity in the larger secondary portion of the runner.

 

What application did that come on? S30's were all SU'd. Even 260's. I'm thinking performance sedan, like 240K or something along those lines. I have a serious case of the "I want it's" right now! You bastard! I want that manifold and carb now. lol

[woldson]

Well I guess there is a frist time for everything, Tony D found something new:)! I never thought I'd see the day. (I'm being sincere, just in case)

[Hotrodpez]

I'm going to go out on a limb here and suggest something my twisted mind just came up with...

 

Picture this:

 

Arizona Z manifold

 

With a Weiand or Whipple long-snout blower on top

 

And dual down-draft Weber 44s on top of that sticking out of the hood... with long chrome air horns...

 

[Noddle]

What application did that come on? S30's were all SU'd. Even 260's. I'm thinking performance sedan, like 240K or something along those lines. I have a serious case of the "I want it's" right now! You bastard! I want that manifold and carb now. lol

 

My 240K GL did not have a manifold like that, not sure about the 240K GT version though, I was lead to believe the 240K GT had longer runners, than the 240K GL.

 

Nigel

[ozconnection]

Oz delivered 240k's never came with 4 barrel manifolds. This ones gotta be jap spec only IMO.

[ozconnection]

I'm going to go out on a limb here and suggest something my twisted mind just came up with...

 

Picture this:

 

Arizona Z manifold

 

With a Weiand or Whipple long-snout blower on top

 

And dual down-draft Weber 44s on top of that sticking out of the hood... with long chrome air horns...

 

 

Something like this you mean?

 

http://uk.youtube.com/watch?v=YBwWXD_Rq7Y

[Hotrodpez]

Something like that... I dunno about a 4bbl carb at a 45* angle though.

[ozconnection]

Yeah, I couldn't figure out whether that guy uses the carb as a throttle only or what?

 

I can't really see the carb working at all properly mounted at that angle?!

 

Perhaps he's using LPG or fuel injectors somewhere? Dunno.

 

Custom built manifold designed to keep everything under the bonnet by the look of things, hence the angle. Still, it runs but I haven't seen any more vids of this machine. Love to see it down the 1/4 though! And the sound.

[Tony D]

That's the old JCR intake with a Camden Supercharger on it.

Likely it's a TBI throttle body, they originally came with a Holley Projection unit (Analog EFI Controller).

I have seen Carbs on that setup, a 650 Holley with some additional solenoids dumping fuel into it (the ProJection had a rather low upper horsepower limit...) for higher boosts. THey used a spacer under the carb to level it out.

 

I have a TERRIBLE internet connection here in Morocco(go figure, huh?) so watching the 9 minute video that guy posted is out for the time being.

 

I don't think Lagos will hold anything better for my layover...and Bonny Island in the Niger Delta... Well, someone stole my Malerone, 5 1/2 pairs of socks, my 2008 MSA Shirt, one of my new Dickies Denim shirts, and a pair of jeans so I'm lucky I'll be clothed, much less have a supply of anti-malarials to keep me from getting sick. I don't think Internet will be extant. I'm more interested in getting my malaria medicine. Dammit!

[Hotrodpez]

Ah... it is this:

 

I want one of these intakes. Anybody got one for sale?

[Hotrodpez]

The JCR online catalog- supercharger page:

 

http://www.jimcookracing.com/catalog/page24.html

[ozconnection]

Ah... it is this:

 

I want one of these intakes. Anybody got one for sale?

 

Gawd, that is lovely, how much is the washing machine?

 

And then add this to the top of that eaton look alike (or is it?)

[PanzerAce]

The JCR online catalog- supercharger page:

 

http://www.jimcookracing.com/catalog/page24.html

 

Anyone know how much those are? Seems like it could be fun to slap onto a junkyard parts motor...

[Hotrodpez]

I dunno if they even make them anymore. I sent JCR an email, but still have no reply. Might have to try to find a used manifold and yank a supercharger off a Mercedes or Toyota.

[ozconnection]

Hey Tony D, you're a bit too slow.........I just bought this on Ebay!

 

A good sandblasting to freshen it up should have it looking like new in no time. Then perhaps build an aluminium plate to adapt the Holley (similar in layout to the Clifford manifold) and I can't wait to try it out.

 

I'm also considering cutting a slot down the middle on the carb mounting surface so I can slide an aluminium plate to create a dual plane setup, like the Arizona manifold. All stealth and reversable, of course.

 

I wonder how large the port runners are? I'll have to write back on this when the manifold arrives here.

 

Until then........