650 holley double pumper or 48 dellortos with bigger jets in them...which 1 is better?

my buddy thats rebuilding my dellortos made me an offer for his holley double pumper $500 or should i just throw some bigger jets in my side draft?

what do you think?...

 

Dell, no contest.

 

What are you using it for? Specs on the engine? We need more info.

 

Yep more info is needed. Side-drafts are good for certain applications and 4 barrels...well there good for just about anything! However a 650 dp on a stock 12a not a good choice.

 

sorry...

well its for my 13b 6 port
it for my gsl
i want to use it for autocross and drift but maintaining its street use...

well right now my motors just polished and race ported(right now i got holley 600 since im rebuilding my dellortos, an i like the response and power from my dellortos)
maybe around febuary or march it should be bridge ported and semi peripherial ported...

but my friends carb is a holley 850 sorry i said 650 before but its an 850 double pumper

and when i do get my motor done i plan to put bigger jets in my dellortos and a few other things...

so what do you guys think is a better application...

 

First off, 650 is too big for that motor. 600 is better.

I'd stick with the Dell if you are into autocross, as Holleys tend to flood when taking left turns hard.

 

Ditto................or go edelbrock, but not holley...

 

850 is WAAAAAY too huge, especially for autocross.

If you think you bog *now* when you come out of a decreasing radius corner at the bottom of 2nd, you'll have a hell of a time even with a 650cfm getting that going.

Honestly, I would go much smaller. If your "race port" is big enough, you *might* go for a 600, but you're not going for high load and high rpm flow for top end, you're looking for something versatile.

Versitility is what 4bbls do best, so I'd go for a 4bbl of a smaller size. It'll give you an easier time at the low end when coming out of corners. Just my opinion, I'm no expert.

Jon

 

ok ok
so we tested the carb
its an 650 holley with 86 primary and 76 secondarys
wich makes it flow 850cfm
so yes its basically an 850 holley lol
but it did flood the engine
so...
we changed the jets
we put 76 i think for primary
and 67 for secondarys

we took it for a ride and damn...it was fast but was bogging
so we checked da plugs they wher bad we sand blasted them then went for another run
it was perfect
so...
went to the track friday orlando speedworld
ran 2 times
first time ran a 15.6 reaction was bad shift didnt go into second...and tires werent hot enough
so...
2nd rn ran a 14.6 reaction was better than first time tires where hotter still coudnt get second gear in right but for all that drama i was happy with 14.6 beause i know she runs good

what i did at the track was change the plugs for new 1's
didnt have an oil pan so i couldnt change oil
i had 3 gallons of race fuel
lol as soon as i got to the track i ran out of gas but thats good cus that allowed me to run pure race gas
we tuned the carb
no bogging
just acceleration going side ways between shifts
oh and on the way home took a few turns to see how the carb will do
and...
she did well
no flooging no bogging
so...
i decided
to keep my dellortos
and buy the holley
with the set up the carb has now its about a 700 or 750

mind you all i have is street port
polished intake and housings
headers
and sum cheap tire on the rear...
so 14.6 with shity reaction and messed up shifting she did good
now time to work on me
oh
i messed up shifting cus i was pulling towards my hip
in a rx tranny theres is a slight curve between 1st and 2nd gear
so in order to not get stuck on that curve pull down but stik ur elbow out i had my elbow in which made me pull at an angel...its ok just got to practice
but that was my first time drag racing
been around it sine i was lil but never actually ran on one...

 

Talk to Bad 83, he has a 650 on a stock port 12a and it pulls pretty even with my Dellorto on a stock port 12a. He doesn't have any bogs or issues that I know of. Its proof that you can run a 650 on a stock port 12a if you tune it right. I'm sure he'll come along at some point and describe whats he's done to it.

 

Your primary and secondary jets are too big. You need to test and tune with different smaller size jettings. What size squirters are you running? Taking corners shouldn't be too bad with the 650. They should have center pivot floats in the bowls. Need more info.

 

Why are you running race fuel in a carbureted 12A. The LeMans 787B ran on pump gas and kicked ***, I think you would be fine with it as well. You really only need to run higher octane if you have a turbo or have really really advanced the timing, which you shouldn't have on a street car.

This is what Sterling said to me when I told him I wanted the largest carb possible.

"Massive excess" kills your low end. Period. A carb that's too big will give the air but not the velocity needed to pull in the fuel. The engine should be mated with as small a carburetor as possible that will match the theoretical breathing capabilities of the engine @ 100 VE. At that theoretical mathematical configuration, the carb should never be maxed out.
Watch, I'll show you:

12a rotary max RPM = 9000
12a rotary cid = 70
That's 70 cubic inches each rotation, times 9000 RPM, = 630,000 cubic inches per minute.
12 inches x 12 inches x 12 inches = 1728 cubic inches per cubic foot.
630,000 cubic inches divide by 1728 cubic inches per cubic foot = 364.58 cubic feet per minute.
That means that theoretically, a 365.58 cfm carb would be maxed out on a 12a rotary running at 100% Volumetric Efficiency @ 9000 RPMs.
Now I say "theoretical" because the carburetor would have to be absolutely perfect - a "theoretical" perfect, at that. And no carb is perfect.
The stock Nikki flows 313 cfm. Mine flow 465. It doesn't really have to, and probably never will on your engine. What's most important is how well I've configured it to flow between 120 cfm and 360 cfm, because that's where you'll ever make power on an unpinned, NA 12a rotary; between 2800 and 8700 RPM.
What makes my carb better than the Holley 465 is that, even though they both flow the same, my primaries are much smaller and better shaped, so the Sterling has much better velocity going through it. This means greater signal to the main (fuel) circuit, better atomization, and better introduction into the manifold. The Holley's primaries are the same size as it's secondaries

I just bought one for less than your paying for yours. I'm not about to start bad mouthing a carb I've never driven, or your decision, but I would be willing to put it up against even a monster carb like your 650. If your going to autocross, your going to want alot of low/mid range power, but a bigger carb will only do you more good at the high end. Just my opinion of course. Good luck. Post some time slips when you get it dialed in.

 

umm guys...i have a 13b 6 port with headers
streetport, and polished housings
ok and the 787b was a 4 rotor...
650 isnt to big
i have the right velocity
so guys saying that ihave too much air...um no
1st of
it stock ports just polished
and a bridge port does what?...allows more air flow
a semi peripheral does what adds more air..
a peripheral port does what...adds alot more air

so u guys are way off
my 48s had good acceleration and spun tires goin to 2nd gear
the 600 holley made the car more torquey
the 650 did all that an more...but i did use more gas
point is
the 650 modified wasnt to much
had good fuel flow with the new jets
good aceleration
good torque
and did as well as my dellortos while hittin sharp turns
guys i test my stuff, compare and contrast...
if that holey is doi good now
when my engine gets ported i will put slightly bigger jets
cause i will need more gas
oh...and im not doing a 6 port turbo...
i getting a 3gen or 2nd gen turbo motor then im runnin a turbo
...this friday im oin to the trac again to get a good time, good reaction time, perfect shifts...after i get that time then im gonna run a 75 shot to see how she runs...
guys...
im just testing, and from what my results the 650 modified did really good...oh and im also using a 1 inch plate...with a j tech intake manifold...

 

see 12 a handles power real good...
and u can use alot of nitrous on that motor
but like i said
i have a 13b
oh my friend had a 1st gen stock
he threw some slicks on it
tuned the stock 2 barrel
and he ran a low 12
...im want to run 12 sec all motor on street tires...hell maybe even better lol

 

Actually the point of my mentioning the 787B was because I can't seem to fathom why you need race fuel. It simply being a 4 rotor has absolutly no bearing on the type of fuel used. Also if you do the same calculation as I posted and just substitute the values for those of a 13B then you'll see that a 650 is able to flow plenty of air, but your engine, in N/A form, can only flow X amount of air. So regardless of the porting or carb size, there is a limit, period, to the amount of air you can shove into your engine without forced induction. As Sterling told me, the best carb, is one that can max just past WOT, so one that flows only slightly more than your engine can at %100VE, which is something no engine can do, simply because nothing is perfect. I was only posting that equation for the sake of an example. This is just what I've gathered in reading, and I'm not asking to be proven wrong, just offering some food for thought. Also how do you know you have the right velocity? Good luck dude.

 

600

 

Not listening again are you? The Dell will give overall better perfomance than the Holley will, especially if you autocross it. If you use the Dell, along with the RB UIM, you can keep working aux ports and have more lowend than you will get with the Holley, and greater overall performance.

 

I agree with a Dellorto unless you are planning to go straight (drag racing). I prefer a Weber 48 IDA. Sell your Dellorto and get close to buying a Weber IDA, instead of spending $500 on a holley. Go buy a new manifold, jets, etc. You will have a NEW system that can't go wrong........

 

Just make three rights

 

well i ran 13.9 2 days ago t tha trac...my tranny wasactin up so ihad to granny shift and my bak end was coming out the 100 shot of nitrous worked good
...im still experimenting with the carb...waiting for my dells to be thrown on...but my ain focus now is my suspension ...

 

...Did he just say "granny shift?"

 

Last I checked, most granny's drove automatics.

 

Wait....

You arent saying you want "dual" Dells are you? Maybe I am mistaken, but unless you are already PP'd or BP'd dual 48's is as much overkill as a 650.

What everyone is trying to say is, the engine will only accept so much air and fuel before you are just wasting it by dumping more in than it can swallow efficiantly. Sure it "feels" faster, but you could be going alot faster with a properly tuned setup.

Or you could just start double clutchin and stop granny shiftin, and use some more nawz. Heck then you would need quad 650's and run nines man..... (j/p..)

 

na
i was askin abou the dual dells for a fully ported race motor
the 600 was good
but the 650 felt alo better... im going to check th hp difference when i get a chance
but she didnt bog or anything jus waste gas lol
but dnt worry im keepin my dells makin the jets fatter
but i do wnt that holley lol
but i balieve if it works good nowit will work beter when the motor is done...
merry christmas everyone!!!
oh umm im sellin a full drag car for 2300 it uns 11.50 best time was 1050 it has a 12a bp with 600 holley and blah blah blah jus hit me up for more info...
nuthings wrong with it
im jus not into drag like that...