SU EFI Manifold Update

[Daeron]

I am all about budget road racer.. I just have lost even that much faith in those filters. I picked up a Honda CRX for a DD over christmas; i haven't gotten it on the road yet (a week or two away) but it came with a new Fram filter sitting in the back. I haven't thrown it away YET, and I must confess that already having the Fram makes it tempting to just stick it on there with some fresh Wal-Mart oil and a bit of Sea-Foam or ATF, run that for 100-150 miles, then drain and change... but I JUST can't put that piece of orange on there.

 

Any more, anytime I need oil, I hop online and go to the websites for Autozone. Advance Auto Parts, and Pep Boys (or any other local chains) and find the one thats running the cheapest "oil change" special. Its like grocery shopping... At ANY given point, SOME store has either beef, chicken, or pork on sale at ALL times.

[z-ya]

Got the car back on the dyno. I'm impressed with the midrange torque increase of 20ft-lbs. Peak power RPM shifted up 500RPM, which gained 11HP. Car pulls much better, and sounds amazing at 6000RPM. Th dotted line is last years pull with the 280ZX NA manifold and 60mm throttle body.

 

 

You can read the writeup Giles at Holy Roller did.

 

http://holyrollerdyno.com/Holyroller_Dyno/Tuning_Sessions/Entries/2009/4/11_ZCCNE_Club_Car.html

 

 

Pete

[Drax240z]

Wow, those are some nice results! Never mind the 11hp peak, but look at the area under the curve, especially at high RPM. Near redline, you've gained around 25rwhp, with around 20rwhp gained from 5750rpm up to 6500rpm. Huge. The 20+ft-lbs of torque at the low end is impressive as well.

 

This sure drives the dagger into the heart of the log manifold/60mm TB setup in my opinion. I'll bet it feels like a different car.

[z-ya]

Yea, it does feel a lot better. Engine pulls much harder. Still have that dip in the power band though. AFR is consistent at 12.5 - 13.5 across entire map. Could lean it out in a few areas to flatten the torque curve a bit but I would rather have it run a little rich and not have to worry about detonation on the track. Got a track event in a couple weeks.

 

The ZX manifold I had on there before was one of those tapered manifolds. It port matched to the head. The new setup is also port matched. Running 48mm Weber velocity stacks and mesh filter screens. No air filter. There is no restriction on the intake. I think this is what pushed the peak power RPM up 500RPM.

 

Pete

[Daeron]

Still have that dip in the power band though.

 

nice update!! Rhetorical question.. What the @#*(%*@!(!~!!!! happens to nearly every L6 at 3800 RPM to cause that torque dip!???

[Xnke]

I noticed that too. Only very rarely do I see dyno charts that don't have a dip somewhere between 3500 an 4000.

[Tony D]

Cam Timing? Our Bville car has a similar dip but the dyno operator thought it was electrical as it was nowhere to be seen on the Weber chart we ran.

When we swapped the head/cam to the 2l, the same dip moved higher in the rpm band, making me think some cam issue rather than an electrical one like first surmised. It's around 6K on what we have now. Interpolating that 'above the dip' you still have at least 3K of useable pull, that seems about right. Ultra-close ratios and shifting above 9300 keeps us from hitting the 'dip' and loosing acceleration time.

 

We did the same: more fuel, less fuel, more timing, less timing. What seemed to make the biggest difference was a 2 degree change in the cam timing at the sprocket. We went in 2 degree steps advanced and retarded from 'straight up' as defined by the cam card and indication. I think it was 8 degrees either way. We settled on the position that gave us the least dip in power.

 

(Though I don't recall the Webers doing anything near that pronounced! But that was 10 years ago when we were running them!)

[1 tuff z]

very nice indeed pete. what events [and where] you & john running this year?

 

would be great for you to post video of the new setup so we can all feel the power!

[z-ya]

nice update!! Rhetorical question.. What the @#*(%*@!(!~!!!! happens to nearly every L6 at 3800 RPM to cause that torque dip!???

 

Yea, I know. Tried adjusting the AFR a bit in that area and it made no difference. AFR is around 13:1 there.

 

very nice indeed pete. what events [and where] you & john running this year?

 

would be great for you to post video of the new setup so we can all feel the power!

 

We are doing NHMS a lot. First one of the year is 4/30. COMSCC is at the Glen today! I'm working..... Not sure if we will do any away events this year. Going to tail of the dragon in May (would love to drive the race car on that road!)

 

Yea I thought of that on the way home from the dyno. Should of had Brad video the dyno session. Sounds sweet. I'll do some in car video this season for sure.

 

Pete

[ozconnection]

Just out of curiosity, and something that I found out quite by accident, have you ever explored the possibility of blocking off one of the balance tube ports on the manifold.

 

A thin aluminium spacer for both sides, one cut so all the vacuum ports etc still work but the other side uncut to block off the connection between both groups of runners.

 

Why do I ask this? If I'm not mistaken, the balance tube was designed to do just that, balance the reversion pulses out which would adversely affect the carbs and their proper fuel metering. Now that you have EFI does that need matter any more?

 

I would see this as a tuning option you have at your disposal. If you're lucky, you may be able to remove some of that dip in the power curve I can see (and you mentioned) on your dyno results.

 

The texts describe this as a 'dual plane' setup, the term being applied to V8's and their manifold configurations. But when broken down to just its fundamentals, it refers to the complete separation of induction pulses from one 'bank' to the other. In our case it's cylinders 1,2 and 3 and 4, 5 and 6 that are separated. The firing order falls into this nicely, so the two manifold groups have exactly 120 degrees of separtion and the pulses are evenly spaced.

 

Cam timing will also play a part, the closer to stock figures, the more profound the effect, but still worth trying on a modified engine using this manifold IMO.

 

Cheap, easy and quick to do, I found this to be a worthy mod to my car long ago when I ran twin carbs.

 

Now running an Arizona manifold with a Holley, I believe I achieved the same effect, with a good range of power and plenty of torque. Try it for yourself and report back your impressions.

 

Cheers.

[Daeron]

Just out of curiosity, and something that I found out quite by accident, have you ever explored the possibility of blocking off one of the balance tube ports on the manifold.

 

A thin aluminium spacer for both sides, one cut so all the vacuum ports etc still work but the other side uncut to block off the connection between both groups of runners.

 

Thats a GREAT idea!!!

 

I don't know if I think it will have a great effect; I honestly have a doubt or two about that (but it wouldn;t be the first time I was wrong.) But maybe my doubts are just questions.. Why would splitting the intake tract in twain be beneficial, when it seems to be a detriment to install headers that do the same thing, and connect both output pipes to a divorced twice pipe exhaust system?

 

Even if I am right, your idea is a FANTASTIC thing to try "as a tuning option," just like you said. You never know what sort of effect it might have and it probably isn't drastic enough to be judged as a "bad" enough change to outweigh any potential benefits. It is certainly easy enough to try the next time the engine goes to the dyno.

[palauoriginal]

any vids yet ?

Edited March 17, 2010 by palauoriginal

[z-ya]

any vids yet ?

 

 

I will have it back on the dyno this spring and will take some videos.

 

Pete

[BRAAP]

Any updates Pete?

[z-ya]

Any updates Pete?

 

It's been running great for two road race seasons. Probably well over 1000 track miles.

 

Here are some current photos:

 

 

 

 

Also had it at the Convention this year in Nashville. When JR Mitchell (Bob Sharp Racing) saw the dual TB setup he said "Cool". A man of few words. But he competed in the autocross with it, and really like the throttle response.

 

Anyway, we are looking to do some vintage races next year, and the EFI will have to go (unless we want to be running with IMSA and GTU cars). I've acquired a bunch of Bob Sharp parts, including an E31 head and Mikunis, so this is probably the route we will go next year. See:

 

http://forums.hybridz.org/index.php/topic/95308-bsr-gtu-e31-head-images/

[G-rib-73-240z]

Thats a GREAT idea!!!

 

I don't know if I think it will have a great effect; I honestly have a doubt or two about that (but it wouldn;t be the first time I was wrong.) But maybe my doubts are just questions.. Why would splitting the intake tract in twain be beneficial, when it seems to be a detriment to install headers that do the same thing, and connect both output pipes to a divorced twice pipe exhaust system?

 

Even if I am right, your idea is a FANTASTIC thing to try "as a tuning option," just like you said. You never know what sort of effect it might have and it probably isn't drastic enough to be judged as a "bad" enough change to outweigh any potential benefits. It is certainly easy enough to try the next time the engine goes to the dyno.

 

 

has anyone ever tested this? because i am doing a similar setup but with only the su intake and j30 throttlebodys have to find room for injectors before the flange, and removing this would help.

 

Thanks for any answers givin.

 

Thomas Gribble

[ozconnection]

has anyone ever tested this? because i am doing a similar setup but with only the su intake and j30 throttlebodys have to find room for injectors before the flange, and removing this would help.

 

Thanks for any answers givin.

 

Thomas Gribble

 

Seems like you'll be the first then!