Grey Goose

I had my Edelbrock Performer TBI flowed today. The manifold has been bored to 2’, other than that it is completely stock (no porting or gasket matching has been done) and here are the results:

Port #1 – 215.0
Port #2 – 246.6
Port #3 – 234.7
Port #4 - 223.7
Port #5 – 216.1
Port #6 - 218.7
Port #7 – 211.4
Port #8 – 209.6

Truth be told I was expecting it to be a lot worse…

I looked everywhere for these numbers and simply couldn’t find them anywhere. So for those of you that have ever wanted to know what the 3704 flowed, here it is…

91RS5spd

Id be interested in what the stock flow numbers are, i just installed one of those intakes my self.

Grey Goose

Based on the conversation I had with Bryce while he was working on my manifold, the 3704 flows a hair better then the factory manifold with the same 2' bores.

ownor

iTrader: (5)

Interesting piece of info! Thanks for sharing with the TBI community

FWIW, the cylinder bank of #2-#8 gets an average flow advantage of 5 CFM compared to the other bank.
Just noticed this is most probably due to #2 flow, so well.. FWIW

thomas1976

Isent that less then the stock TPI intake?

Grey Goose

No problem. Like I said I’ve looked everywhere (TGO, FSC, Magazine articles, etc.) and could not find numbers on this intake. There are so many different opinions floating around out there that it’s almost impossible to determine what the 3704 is capable of performance wise. Now I have definitive information and I’m more the happy to share it with everyone.

The flow numbers on port #2 are a little skewed because just after he flowed that particular port I noticed that the piece of clay he had used to block off the vacuum port on the runner had fallen out giving the air another place to escape therefore slightly increasing the cfm reading. So the actual reading would more than likely be in the mid teens to low twenties much like the other ports.

Correct, the factory TPI base flows 230-240.

Saabster

iTrader: (2)

So how much is a hair better? And what difference does the 2" bore make over the stock bore?

Also while this does flow less than a stock TPI base, it still flows more than a stock LO3 port, so does it really matter?

Damon

Thanks for sharing this information! And even taking the time to get it flowed in the first place.

Agree- it's actually a little better than what I would have expected. But definitely nothing you're going to be making 500HP with.

I think comparing the flow numbers of that intake to just a TPI base manifold isn't quite apples-to-apples. A TPI would need to be flowed with the runners and plenum installed (no TB) for it to really be a valid comparison. You know, everything past the throttle plates.

Grey Goose

A factory manifold with 2’ bores flows roughly 180-200 cfm. I don’t have any data on a factory manifold at 1 11/16 then bored to 2’.

TPI numbers are completely irrelevant to this discussion.

If one were inclined to have the 3704 fully ported for about $500 you would see flow numbers around 250-260 cfm which would support some decent horsepower depending on what heads/cam you were running. However the biggest problem with the manifold is the plenum design. The air becomes so turbulent/unstable it was actually audible on the flow bench. It sounded like popcorn popping.

I need a manifold that flows upwards of 300 cfm and no matter how much money I throw at the 3704, its not going to happen.

Saabster

iTrader: (2)

So what I read from this is that unless I want to go in excess off 300 BHP, or swap for better flowing heads, Putting on a 3704 is probably nearly useless in terms of power. In fact it's probably best just to leave the whole intake tract alone and just mod the exhaust.

86firebird350

Really good post. Thanks for sharing. Does anybody know if there are any differences in the design and consequently the flow numbers between the edelbrock and, say the holley or gmpp TBI intakes? Or are they all pretty much the same?

Grey Goose

Correct. One of the guys in our group installed a 3704 on his LO3 and dyno’d it before the install and after. The car went from 158RWHP to 160RWHP.

My recommendation would be to invest the money that you would spend on this manifold in headers, y pipe, and a cat back system. As far as induction goes, there is definitely something to be said for the ultimate TBI mods and ultimately utilizing a 14 x 3 open with a flat base. Based on what I have experienced the throttle response is much crisper and as far as horsepower goes it’s rumored to yield an 8-10RWHP improvement at the wheels.

The only data I have to support this is what another guy in our group has a 90 RS (LO3) with custom chip, vacuum adjustable fuel pressure regulator, injector spacer, SLP Headers 1-5/8" , custom 2-1/2" Y-pipe, 3” cat back, LT1 fuel pump, and an 1995 LT1 cam. The car dyno’d 201RWHP through the factory air cleaner and 211RWHP with the factory air cleaner removed completely. This is a sold documented 10RWHP increase on this particular vehicle. Now this is running the vehicle without any form of air cleaner on it.

So switching to an open element on a flat base on a stock LO3 could feasibly net you an incredibly optimistic 4-7RWHP.

The only reason I even entertained using the 3704 is that I live in California home of the smog ***** and I don’t want to have to **** with the throttle linkage/kick down linkage by moving to a carbureted manifold that has EGR provisions.

Saabster

iTrader: (2)

Very interesting.

There's defintely something to changing the air cleaner. The stock single pipe air cleaner is actually smaller than the opening of the throttle blades. The limit seems to be around 200 whp as you've discovered. Below that it won't make a difference, and above the disparity will get larger and larger. This is actually very valuable information that I hadn't been able to find, thanks a bunch.

As for porting the throttle body, I've always be dubious of this personally. The stock unit flows 490 CFM, and math says that should be enough for more than 300 BHP.

I'm with you on that, none bolt-on manifolds are a pain. The 3704 does have an advantage of being made of aluminum rather than steel. I was going to get one myself, but because of this thread I won't bother.

Grey Goose

No problem

It all comes down to whether or not you base flow on 1.5hg or 3.0hg which is an extremely sensitive subject on this board. One which I don’t wish to get involved in…

Lets just say that if you happen upon a used 3704 for a price that you simple cant pass up. Stretch the bores to 2’, clean up the casting flash, and port match the heads and intake to 1205’s you’d have a great little intake for an LO3 with an LT1 cam, full exhaust, larger throttle body, 3.42’s or better, and some tuning you see mid to low 14’s all day long…

Saabster

iTrader: (2)

Well yeah, I mean it's clearly not bad.

anthonyrs

I AM ABOUT TO BUY ONE OF THESE MANIFOLDS FOR ONLY $1OO AND ITS LIKE NEW. NOW SHOULD I OR NOT? ANY HELP. I HAVE A CAM AND HEADERS AND OPEN ELEMENT AND CHIP. THANKS

Grey Goose

I purchased mine for $50 with 2" bores. I wouldn't pay $100 for this manifold now that I know what it flows but it's your money. Will your combination benefit from installing it? Yes, but not much...

thomas1976

So how much hp do such numbers support?

91RS5spd

Wouldn't you benefit roughly the same if you port matched, and bored the stock intake to 2' as you would with the 3704? Or is there something about the 3704 that will allow it to out flow the stocker even if they were both modified the same?

Just wondering because i have my stock intake still and down the road i may want to work on it a bit.

Birdstheword

so , in the end , is it really worth spending $300 on the #3704?

d00012

Pretty much it's better to get this one for $70 less?

http://www.summitracing.com/parts/HLY-300-66/

Saabster

iTrader: (2)

Well what do we know about that one? To start I don't see a line for the brake booster, which is a hassle.

d00012

You know what, I didn't notice that on first glance...hmmm.

I H8 WWD

iTrader: (5)

Edit:

Sorry, made a mistake. I am getting the 3706, which will allow aluminum ZZ4 heads to be mounted as long as I mod the angles of the manifold bolt holes which isn't hard either. This will be used with a TBI adapter and the Holley 670 (and matching ZZ4 cam). By then my smog wont matter, can we say Historical Plates...mwah hahahaha.

Anyway I still don't think the 3704 is a bad buy. Its lighter, a bit more power. Smog legal. Not stock.

Ronny

iTrader: (1)

Now I question what the Holley tbi will support. Holley port exit size is .02 larger in both dimensions. Edel rated to 5500 rpms and Holley at 6000 rpms. I run the holley and it does rev cleanly to 6000 rpms(350 CID). Holley height is 5.4 inch and Edel is 5.1. Possibly runnner lenght is a bit longer on Holley

On crossfire forum the replacement manifold options and original CF ported and non ported are listed for flow. If I can find I will post

86firebird350

im leaning towards using the holley intake myself. Saabster mentioned that he didnt notice a line for the brake booster. does this manifled not have one? if not, what did you do to get around that?

Ronny

iTrader: (1)

There is a VAC source to the passanger side of distributor. I also tapped into that fitting for my VAFPR need.
http://holley.com/data/products/pict...arge300-49.jpg

d00012

Do you use the Holley tbi unit, too? Is it really only good until 250hp like it says on their site? Seems like a waste of money if it's only good to that amount of power.


Good job on the flow chart for the 3704, I was actually going to get it, might rethink it and find some vortec heads and get the gmpp manifold.

Ronny

iTrader: (1)

Yes I use it. I never saw a HP listed on their site? Only RPM.

d00012

http://www.holley.com/types/Avenger%...%20Systems.asp

275hp, not 250.

Or do you have the 3210 model?

Ronny

iTrader: (1)

That is the "system". apples and oranges. I believe the Holley TBI system is limited by fuel rather than cfm of manifold.

As a side note Holley rates the system at 670 CFM. Think of what a 670 CFM carb can support. I suspect quite a bit more HP than 275.

ownor

iTrader: (5)

+1, that's also the way i understood it.

from what i recall the 490 CFM of a stockish TBI unit are rated at a different pressure than what carbs are usually flowed at? would also be interesting what Holley tested theirs at..
interesting info in here about the Projection TBI manifold vs. this Performer TBI.

Ronny

iTrader: (1)

I forget which ends up with better rating. Nor do I understand why Holley or any other mfg would rate/test differently TB's than they would for carb.

My Holley shows key on 96 MAP(atmosphere) and at 6000 rpms shows about 94 MAP I recall so little restriction apparent. Not sure if my 7.4L TBI or the Holley manifold flows lesser.

svwayne

The response I got from holley was that the 300-66 intake manifold is NOT a stock replacement intake. Fabrication is likely required for brake booster, EGR fitment/clearance, heater hose routing, ignition coil mounting.

This is the actual quote from the Holley rep -

"Stock TBI will bolt up. The 300-66 is not a OE replacement. There will be problems with hookups and emission controls."


If I've got to go through all of that I might as well run a carb'd intake with a TB adapter plate.

Ronny

iTrader: (1)

I needed to use Holley EGR blockoff plate as I am non emishions as well as use a throttle cable universal bracket I bought from Edelbrock. GM TBI unit bolted right up. That was it.

Grey Goose

This is one of the best posts I have come across on TBI flow. It will clear up any questions you might have.

https://www.thirdgen.org/forums/tbi/...tbi-alive.html

Grey Goose

That’s a loaded question… there is virtually an infinite number of motor combinations that one could use. So it’s impossible to give you an actual number. The best I can do is give you a range based on what people I have spoken to have found using the 3704. On a 350 with aftermarket heads, mild porting on the heads, cam, 1.6 rockers, 3704 bored to 2”, port matched heads and intake to Felpro 1205’s, big block throttle body and proficiency in the art of tuning, 270-320RWHP

Correct, if you are looking to use a factory style intake and not convert over to a carb intake. Have your factory intake bored and port matched.

No it isn't. Invest that $300 into headers and exhaust.

I H8 WWD

iTrader: (5)

^ Nice

bluers91

So now the question is what is to gain from swapping this intake with the stock one if you already have Headers and a full exhaust? Would it be safe to assume you could gain more than 2RWP?

Grey Goose

Based on actual before and after numbers we put down on the dyno that is more than a safe assumption. It is a fact. On a bone stock LO3 we picked up 2RWHP after installing the 3704. Now since we are taking about the 3704 only, should you decide to install one and you have headers/cat back installed. You would need to dyno your car as it is now and then once you have installed the 3704 dyno it again. This is the only way that you will know what the 3704 yields with your particular combination.

More often than not people go to the dyno to get a baseline with their stock motor and then go back once they have thrown a pile of mods at the car. Sure they make more horsepower but there really is no way to tell what mod made what horsepower. Strapping your car down to a dyno isn’t cheap. believe me I know… but it’s the only way to truly tell what individual mods make horsepower. It cost me $50 to have that 3704 flowed but it was worth it to me because I couldn’t find the information anywhere. I was happy to share the information with everyone here because TGO has supplied me with a wealth of information that my vehicles and I have benefited from. It’s a give and take…

bluers91

I just did the full exhaust on my car and there is a real difference. My next mod was going to be an intake, but if there isn't very much of a gain then there is really no point. That is why I would like to know if anyone has measured the gain after swapping an intake on a car with a full exhaust. I also wonder how a performer carb intake with a TBI adapter matches up with the 3704.

Grey Goose

Headers & exhaust combined will net the most power on a stock LO3 period. Pitch the factory air cleaner in exchange for an open element with a flat base and your LO3 will have a completely different personality. You’re not going to win many streetlight confrontations against late model V8’s or even V6’s for that matter but you’re car will be much more fun to drive.

If you are a purest and want to take your LO3 to the next level instead of going with a 350 like many people do. Then I would have the intake bored and port matched to compliment your new cam & heads.

The problem with the 3704 is the plenum design so going with a carbureted performer would definitely be better than going with a 3704. Now keep in mind, there is going to be some modifications that will need to be made to make it work but hey that’s what it’s all about.

bluers91

I already have a free Performer 2101, TBI adapter plate and an LT1 cam. I did an open element years ago as well as the injector spacer. I would love to just go to a 350 but the wife wouldn't really let that happen unless the 305 was dead. One day! So, I collect cheap parts any way I can and slowly build it up for more fun. I know with a 2101 the center bolt holes would need to be enlarged and all, but I would only do it if I think I could get 20ftlbs or so. I was under the impression that that could happen and fatten up my torque across the entire curve. After reading this thread and the results of 2ftlbs more with a 3704 I began to get sceptical. I don't really plan on installing the LT1 cam until I can find a better set of heads (059 vortecs or something else) to go with it with all the extra work involved. I figure an intake swap could be done rather easily to keep me happier for now while I collect more stuff. It took me some time to collect my Hooker 2055's & Y, 3" catback, 3" cat but I got it done. The 3" catco cat was the only new part and cost more than my headers and y pipe. I just got an ALDL cable and plan to get into some basic tuning next. Nothing like hot rodding on a budget.

RFmaster

Very interesting thread - do not mean to hijack it, but would you be interested in flow testing GM 14102182 Aluminum TBI intake? Let me know as it should provide interesting side by side comparison especially if done on the same flow bench!
I should be getting this intake in next couple of days. I am local in So-Cal, near Anaheim. At this time unit is 100% stock (i.e. 1.775" bores), but my plans include boring it out to 2.0" to match BBC TB.

//RF

thomas1976

I would also be curious to see the flow numbers of that 3704 with some sort of "crossflow" opening between the bores. Something like this http://marine-performance-parts.com/...eanerstud.aspx

Similar to what my 91 LO3 had, GM 10108449, made of aluminium with the "crossflow" hole.
https://www.thirdgen.org/forums/atta...lo3-intake.jpg


EDIT around 3 years later:

Thought I add a little feedback from my own personal experience
https://www.thirdgen.org/forums/tbi/...bi-3704-a.html

dctrumpet

iTrader: (10)

I have 4 of the 14102182 intakes that have been bored to 50mm. Already bead blasted as well and pressure tested. We can use one of these to test if you'd like

dctrumpet

iTrader: (10)

I also have a Holley Projection TBI intake that I would love to have tested as this is what I want to install

Grey Goose

According to Dyno 2000 that particular combo should net you just over 200-215RWHP (the program is always +/- 10HP compared to actual dyno results on cars we have dyno'd) which is good for mid to low 14's. Good times

Sure, all I need is the manifold and the $50 to flow it and we’re good to go. Let me know if you are interested.

I thought about that but once I got the results on what the manifold actually flowed I completely lost interest. I actually have the 3704 on craigslist. It needs a new home…

Send me the manifolds and the money to flow them and I’d be happy to take them over and have it done for you. Let me know

dctrumpet

iTrader: (10)

PM me with the info to ship the intakes to you and let me know the cost for flowing them

Gallileo60

Well I sure feel like an idiot, I just bought one from summit along with 1.6 roller rockers.....Before I put the intake on, is there any machining besides boring the throttle holes that can help this intake???? I see the stock one has a hole connecting the 2 throttle bores together.......i was at least hoping it would give me a little better throttle response...i just did the ultimate TBI mods, and adjustable regulator...Can I expect any improvement with the mods, the rockers, and the intake???? Already have a full Edelbrock exhaust, and no pollution stuff..Sure wish I would have read this first...I would be thankful for any suggestions, it is a done deal so I am stuck with the parts now.....Thanks....Tom