webbers against injection.

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Hi all thought you might be interested in our results of a back to back test with 48ida webbers against the new dynaformance webber lookalike injection system.We did not use the original electronics we had an accel ecu and system to suit our requirements and a few mods to the carb injection body.The test was done on a dyno on my new 347 stroker with a fairly mild cam and modest compression ratio the webbers made 450bhp and 400lbs ft torque with injection it produced 490bhp and 428lbs ft torque.
regards mick.
 

Randy V

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Hi Mick,

Very interesting...

Did both the Webers and the Injection TBs share the same CFM rating?

I'm presuming that both were tuned for peak power and A/F ratios...

What were the comparative BSFC numbers?

I ask because this may well be the way I build the next car and other than the dyno testing I've done with Single 4BBL carb vs 4 BBL throttle body - I've not seen a head-to-head comparison...

Thanks!
 

Terry Oxandale

Skinny Man
Interesting indeed. If I'm not putting words in Randy's mouth, would this differnce be attributable to the reduction of the throat size of the carbs due to the chokes? I'm assuming the choke ID will be substantially smaller than the open throat of the ITB (and the throttle plate of both), which could imply a measured performance given the measured difference. Thanks for the info!

I've not even looked at the Accel product for my ITBs. So far the winner for me in my search for an ecu (economy vs effectiveness) is the MEFI marine set-up originally designed for the SBC. Can you describe a little bit about your experience with the Accel (if we're not deviating off topic?)

Terry
 
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Hello Randy
Would appreciate you posting results for Single 4BBL carb vs 4 BBL throttle body power differences and if any fuel consumption and drivability advantages found
Thanks in advance
Dennis
 
Hi terry and randy the webber vs injection test was done on the dyno at huddart racing mike has all the info so the answers to your questions will be posted in the engine /induction part of the forum regards mick.
 
Can someone help me figure out my idle problem on the Dynatek? I plan to check the base timing tomorrow, but I would expect it to be right since Keith Craft built my engine and Dynatek came to them to help tune it.

Not trying to take away from this thread. I like the results shown here, but my car idles at 1600 to 2000 rpm at this time with this system. When I un-hooked my throttle cable it comes down on idle to 1000 rpm by putting pressure on the idle control rod, but even then it won't stay down. Now if I bump the throttle again it will bounce up to 2000 rpm all over again.

Any suggestions? I would like to nip this in the bud tomorrow.
 
Can someone help me figure out my idle problem on the Dynatek? I plan to check the base timing tomorrow, but I would expect it to be right since Keith Craft built my engine and Dynatek came to them to help tune it.

Not trying to take away from this thread. I like the results shown here, but my car idles at 1600 to 2000 rpm at this time with this system. When I un-hooked my throttle cable it comes down on idle to 1000 rpm by putting pressure on the idle control rod, but even then it won't stay down. Now if I bump the throttle again it will bounce up to 2000 rpm all over again.

Any suggestions? I would like to nip this in the bud tomorrow.

Allen,
We did the work and development on Mick's Dynaformance system and what you describe is exactly the problem we had with Mick's.

Bigest problem was that the butterflies and/or the spindles do not line up properly and the small capscrews holding the butterflies were glued in so tight I gave up on moving them for fear of sheering them off. The throttle bodies themselves were not in line with each other so had to slot the two fixed throttle levers to get the linkage to line up, before when you tightened the cross screw it held one throttle body open.
With a bit of massaging with a plastic drift we managed, after umpteen attempts, to get the idle down from 2000 to arround 950, this was with extra springs to put tension the linkage. We did consider unhooking the coiled return springs on the throttle shafts and adding springs to the linkage.

Dynaformance knew about the problem as they have now modified their TB to take a thinner butterfly which is easier to seat, this was done in January this year so if you have an earlier kit, you will have the thick butterflies.

If you look at the Dynaformance software, they pull about 10 degrees of timing out at the last 2 % of throttle movement to help slow the idle, ours idled best at about 22 but had to cut it to 16 to get the numbers down, not ideal. Hopefully this won't be neccesary with the new TBs.

We have developed our system to take Accel DFI electronics (we are the Accel DFI EMIC for the UK ) as anything we do in the UK on a new car will have to pass an emissions or CAT test, the original Dynaformance kit was not capable of doing that. So we now have full IAC idle contol for the idle.
With the throttle blades fully closed we were getting 5% IAC on a 950 idle, so that gives you an idea of the air leakage round the butterflies even after our "remedial work"

If you want to PM me about your idle problem then please go ahead, will be happy to help

Mike
 

Randy V

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Hello Randy
Would appreciate you posting results for Single 4BBL carb vs 4 BBL throttle body power differences and if any fuel consumption and drivability advantages found
Thanks in advance
Dennis

Hi Dennis,

The engine was a 502 Big Block Chevrolet for an Off-Road Truck.
The systems we worked with were a Holley Commander 950 system with a 1,000 CFM Throttle body and a Holley HP 1,000 CFM Carb.
We started with the Carb and tuned it to deliver peak power. Tuned so easily it was amazing. Now with the engine broken in and the numbers stable between pulls we had our baseline.
The Commander system took a full day of tuning to get to work as well as the carb did out of the box, but we were ultimately able to achieve peak power. The rest of the tuning was to get throttle response where we felt was best.
At the end of the second day and the dyno sessions in general - we had selected the EFI system for it's ability to automatically adjust for barometric pressure changes and the lack of problems when working when the truck was not within 10-15 degrees of being level.
With the carb, there was slightly greater torque in the mid-range (maybe 5-7 Ft Lbs) but the overall numbers and fuel consumption were nearly identical between the two optimized systems.
HP was 615 and I believe torque was 640.

It was all about air and fuel - and how much of each. With using the same intake manifold between systems we were able to eliminate that from being a variable.
 
Hi Mick,

Very interesting...

Did both the Webers and the Injection TBs share the same CFM rating?

I'm presuming that both were tuned for peak power and A/F ratios...

What were the comparative BSFC numbers?

I ask because this may well be the way I build the next car and other than the dyno testing I've done with Single 4BBL carb vs 4 BBL throttle body - I've not seen a head-to-head comparison...

Thanks!

Randy,
sorry for the late reply, it's been a hard few days lately!
As Mick says, we supplied and did the instalation on his 347 with the Dynaformance EFI kit and did the development to convert it to Accel DFI.
The Webers were stock 48 IDA off Micks original 331 bolted to the Dynaformance manifold (Pierce) Since Accel's development of the TWM kit for Roush with the same manifold, they now come with a built in vacuum plenum in the lifter valley so it was easy to run the MAP sensor and IAC idle contol, a feature that Dynaformance did not have before.
The 48s had 37mm chokes but the Dynaformance TB allthough still at 48m had no choke, 48mm all the way through. Dynaformance rate them at an increase of 90cfm per choke over a 48 Weber but don't state what choke size they are comparing with. I do think their figures are optimistic though.
We ported the manifold to match Mick's Victor Jnr heads, the original ports in the manifolds are quite restrictive, we know from experience with TWM kits using the same manifold they are only good for about 400hp unported.
The Dynaformance TBs had their long spec air horns, if we are looking for more top end we would try the shorter version next time
Now we are using the Accel electronics we have been able to go to sequential injection with their Duall Synch distributor and all in all have been very pleased with the installation. Terrific throttle response and hopefully vastly increased fuel consumption over the Webers. With gas at about $9.00 a gallon in the UK thats a big plus !
The motor was originaly built for the Webers and we found that the cam was a bit conservative for the EFI, a better cam would have seen 500 plus, maybe the next one !
Mike
 
Interesting indeed. If I'm not putting words in Randy's mouth, would this differnce be attributable to the reduction of the throat size of the carbs due to the chokes? I'm assuming the choke ID will be substantially smaller than the open throat of the ITB (and the throttle plate of both), which could imply a measured performance given the measured difference. Thanks for the info!

I've not even looked at the Accel product for my ITBs. So far the winner for me in my search for an ecu (economy vs effectiveness) is the MEFI marine set-up originally designed for the SBC. Can you describe a little bit about your experience with the Accel (if we're not deviating off topic?)

Terry

Terry,
apologies as above for late reply.
Yes to the above but I think also due to the more acurate fueling with the EFI and better timing control with the ignition managment (we ran a regular MSD with the Webers) made more power at the top end by pulling a couple of degrees out over 6000 at WOT.

Regarding ECM for your system have a look at the Accel Gen 7, as said in the previous post they did all the development for the Roush IR motors and that's the ECM they use.
You can download demo programs from their website www.mrgasket.com and click on the ACCEL DFI logo. I can put you in touch with their tech guy if you need more info.
Mike
 
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