Holley 4BBl Performance

[porkbun]

[grannyknot]

Smart arse

You know what your getting in to, you just have that same sickness most of us do, we cannot leave it alone, gotta try something new.

Can't wait to hear about it.

[porkbun]

But that post actually got me thinking. With SUs the air goes in through the grille and is pulled in at a 90* angle where it enters the intake and is distributed amongst the cylinders. With a 4bbl the air is also pulled downwards at a 90* angle before it enters the intake. From the base of the carb the atomized fuel and air are pulled directly where they need to go since the vacuum is coming from the runners/cylinders and not from underneath the carb. Not sure if I'm making sense since thought of this as I was falling asleep.

Predictions for the 600cfm: Going to have a horrible idle since my cam doesn't pull much vacuum at idle. Throttle response shouldn't be great but it should have a great top end and perhaps an increase in fuel economy? The ribs in the BSR manifold might be restrict the flow too much if I can even open the secondaries

[CelticZ]

Thank you for sharing your experiences with the Holley,

Previously always considered Holleys a rather archaic and neanderthal approach to fuel delivery, (rather like a bucket with a hole in the bottom)

However, having to reevaluate because it just works so well at least based on my own experience with a Holley 1850 on a Arizona Z Car intake manifold but as a Blowthrough using a T4/T5 Hybrid turbo with intercooler on a 280ZX Turbo drivetrain.

The Lokar throttle cable and bracket work much better than the "other" brand, i had the same issue with the black plastic cable retainer.

[porkbun]

Ahh yes the "other" brand which is sold by like 5 different companies. Even had the little nub at the end of my throttle cable pop off. I love spending hours outside trying to rig something up in 30 degree weather...on my birthday! Now I carry old G strings in my car just in case something goes wrong... G strings from a bass guitar! All carbs do pretty much the same thing, its just how well they can meter fuel at the right time. The blowthrough is a cool setup though, Ive heard from a few guys doing a blowthrough setup with a 4bbl and that may just have to be the next step .

600cfm is on the car now. Specifically I have an 80457 which is just the electric choke version of the 1850. Was a bit more work to get it setup properly but thats what happens when you have a big cam. Right now the stock jets are too lean so I cant go over 2.5k . Throttle response is different but not horrible. Initially it feels like "Oh, I didnt realize you touched the throttle" but once you get moving it feels the same as the 390. What this means is you have to blip the throttle before you get moving from a stop. Will give more details as I get them and look forward to doing some flat out runs!

[240260280z]

Holley boosters are better than Weber Venturi's however fuel in air does not like 90 degree turns. It is not desirable for air to do this in a design but it is much worse for fuel in air to take a 90.

[CelticZ]

The blowthrough does make for a fun set up,

it will stumble in 2nd gear at 1000rpm pulling into a parking lot for example, but otherwise below 3000rpm it is docile. I average 20mpg in Los Angeles Traffic, and 32 mpg on the freeway.

[porkbun]

With those fuel economy numbers I think I need to get a blowthrough setup!

Here's a post off of hybridz from a guy who went from fuel injection to a 4bbl and dyno'd both and compared them: http://forums.hybridz.org/topic/52977-arazona-zcar-intake-vs-fuel-injection-long-pix/

Edited May 30, 2014 by porkbun

[porkbun]

Bob Sharp Manifold was less than satisfactory. Great when daily driving but no oomph when flooring it. I think its pretty hard to cram 195cfm let alone 300cfm through this tiny opening

Didnt even try to film any acceleration runs since they were so slow. So far the best manifold has been this one that was on the car when I bought it

But Ive got something else which im excited to try. According to Dave at Arizona Z car:

"The divider in plenum makes a dramatic improvement in low end response, I also opened up the runners for improved top end.

Overall performance is excellent." and something found its way to my door today

High divider: check

Wider opening : check

BSR

Honestly I dont know why there are those stupid little ribs before the 3 and 4 cylinders. In my mind it makes sense that the biggest opening would be the best(which is why the original manifold I had was the fastest) but as you can probably tell by my idea a few posts up, im nowhere close to an induction expert. Had a 600cfm on the car for a few months and finally got my hands on a 465cfm which I think will be my final Holley. AZC is on the car and running but I havent really tested it yet. All thats left Holley wise is to get my hands on that original manifold then triples? 6 motorcycle carbs? Who knows !:stupid:

[CelticZ]

on the holley blowthrough I am using a 600CFM,(modified for blowthrough application) on the Arizona Z manifold and had a rolling road tune up after installing a AFR and EGT gauge.

Without any adjustments it was making a hair over 300hp at the rear wheels using a hybrid T4/T5 and intercooler with aprox 13 boost. This was for tuning, rather than power, the consensus was not to touch anything.

With the holley carb set up being so simple I of course went out and bought a hacked up, barely running, 73 240Z with a RB25DET:D

[porkbun]

Are you using a regular 1850 or one of the holleys modified for blowthrough? I was pricing out the blowthroughs and it seems like my money would be better spent doing an L28et swap especially if the blowthrough carb goes for ~$700 by itself. Interesting idea but im not sure if anything will happen on this car

[CelticZ]

Are you using a regular 1850 or one of the holleys modified for blowthrough? I was pricing out the blowthroughs and it seems like my money would be better spent doing an L28et swap especially if the blowthrough carb goes for ~$700 by itself. Interesting idea but im not sure if anything will happen on this car

Definitely modified