Carburated power

[AFCrain]

In the process of building my L28-et I plan on slapping on a new carb setup on my L26. I'm not going to go into details about the L28 by I'm looking for input on power gains on carburated L series. Any input on the different setups is welcome, eg: SU's, triple webers, 4 barrel conversions, etc. I'm looking for the biggest bang for my buck while I wait for the real power!! Also, please don't try to dissuade me from doing this. I don't care about the extra costs or how pointless it may be. I simply enjoy working on my car, plus if the L28 blows up down the road this could be a good back up.

 

Thanks in advance for reading and commenting!

[Leon]

It would be wise to try a search first as there have been many threads on the topic. Personally, I'll take a good set of triples over any other carb setup.

Edited May 1, 2011 by Leon

[WEBEZEEed]

Best bang for the buck....S.U.s get some from a 70,71,or 72 & the book Tuning the A series engine by David Vizard( following his tips on S.U.s ) and voila! 20-25%. increase in H.P. & torque.That's what my 73 with 173K mi. got. Not counting the price of the book it was all elbow grease.

Edited May 2, 2011 by WEBEZEEed

[rsicard]

In the process of building my L28-et I plan on slapping on a new carb setup on my L26. I'm not going to go into details about the L28 by I'm looking for input on power gains on carburated L series. Any input on the different setups is welcome, eg: SU's, triple webers, 4 barrel conversions, etc. I'm looking for the biggest bang for my buck while I wait for the real power!! Also, please don't try to dissuade me from doing this. I don't care about the extra costs or how pointless it may be. I simply enjoy working on my car, plus if the L28 blows up down the road this could be a good back up.

 

Thanks in advance for reading and commenting!

 

Think about Fuel Injection. Purchase a 4 barrel manifold and put a 4 barrel throttle body on it for fuel injection. Have the manifold machined for fuel injector bungs and tig them in place. I have experience with several fuel injection systems and the most flexible is the Electromotive system. Carbs have rich and lean spots up and down the RPM and load curves. Fuel injection can tune out all the irregularities and is very consistent.

[Tony D]

Seen SU's twist a dyno to 192/196HP on L28's with headwork and a cam.

Had either of them run forged internals and run the rpms higher....I believe they would have broken 200.

 

But this:

 

"Any input on the different setups is welcome, eg: SU's, triple webers, 4 barrel conversions, etc. I'm looking for the biggest bang for my buck while I wait for the real power!! Also, please don't try to dissuade me from doing this. I don't care about the extra costs or how pointless it may be."

 

Sounds a bit of a contradiction in terms. "Best bang for the buck" and "I dont care about the extra costs or how pointless it may be." Seem to me to be totally opposite statements. Which is it? Best bang for the buck, or best bang, regardless? You have to make a decision. The power is pretty much in the head, not what induction system you put on it. The stock system I've seen run cars into the 12's, and spin well near 2X the stock horsepower on a chassis dyno (210 compared with an unmodified 120) --- and in that case, the thing that was changed was the head and the cam, not the carbs. Amazingly they were not altered in any way other than some needle changes for better mixture delivery according to the new cam profile. If they had been altered in diameter, and other tricks, more was available---but the point being, the induction system didn't make the power, it was doubled by headwork and camshaft.

 

You need to look elsewhere if you want meaningful numbers... carbs won't give you much above stock numbers without headwork.

Edited May 2, 2011 by Tony D

[frank280zx]

Like Tony said .. The power in the 'lgata'is in the head ( i.e. work done to it)and compression.

 

since your location states "Okinawa, Japan" Id go to a speciality shop over there, they do magic on headwork.

[ozconnection]

Like Tony said .. The power in the 'lgata'is in the head ( i.e. work done to it)and compression.

 

since your location states "Okinawa, Japan" Id go to a speciality shop over there, they do magic on headwork.

 

You guys take things way too seriously. He's only having a muck around with some stuff.

 

I like what Rsicard is suggesting, an interesting, unusual and functional setup for sure.

 

The Arizona 4bbl is good for the street, providing good low to mid range torque. The Clifford is excellent for top end power. Choose your poison and have some fun!

[Tony D]

Define 'top end power' when it falls off above 6500 compared to triples, and non-forged pistons effectively limits you to that rpm range so 'big gains' are not to be had with carburettion changes, period.

 

That is the long and short of it. This is just another case of someone looking for the 'magic bullet' component they can bolt on and pick up some miraculous horespower bump without dilligent work. Ain't happenin'...

 

The comment on buying the book and learning to tune the car and 'viola, 20-25% bump in power' is about as close as you are going to get---and that's not from some simple bolt-on crap. It's from learning to work with what you have and tuning it properly.

 

When will the myth of 'bolt-on horsepower' die the silent death it so rightly deserves?

[AFCrain]

Sounds a bit of a contradiction in terms. "Best bang for the buck" and "I dont care about the extra costs or how pointless it may be." Seem to me to be totally opposite statements. Which is it? Best bang for the buck, or best bang, regardless? You have to make a decision.

 

I just want to point out that I think you're looking a little too far into it. Since you are and you were nice enough to lend your expertise, I'll tell you exactly what I meant.

 

"Best bang for the buck"~I've already purchesed a great running vehicle for well under what I had planned, but it is still stock under that bonnet(love the Aussies). I'm just looking for some ways to have more fun while the big boy(L-28) is under construction.

 

"I don't care about the extra costs or how pointless it may be."~ It's pretty self explainitory if you ask me. I have money, little to no bills and don't want to see that beautiful, beautiful Z just sitting there. So I'm gonna pick an after market carb setup and maybe a cam, who knows, and have some fun.

 

@rsicard~ Sorry, but I'm already doing the fuel injection. While I am curious about that setup, carbs are usually simpler, even if they are tempermental sometimes. Thanks anyway.

 

@WEBEZEEed~ I actually do have a set of round tops. I will check into that book though.

 

 

I guess I did kind of leave myself open for that sort of feedback. But I'm not looking to turn the stocker motor into a race engine. Just some fun little things I can do over a weekend.

[AFCrain]

I also forgot to mention that, while I do live in Okinawa, I don't have much time left here and most of that will be given up to deployment related appointments and then a move once I get back.

[frank280zx]

Run into a speed shop get a gnose and Kamenari cam gear cams etc etc .. oer side drafts ... while you can! cheap!

It takes a day if that!

 

There is tons of stuff fairly cheap over there and SERIOUS Cash over in the states.

anyhow if you want nice carbs for a stock L26 get some 40 Mikunis or OERS

Edited May 2, 2011 by frank280zx

[WEBEZEEed]

AFCrain, if you decide to get that book I think you'll consider it a good decision.There is a lot of information in it that pertains to most any internal combustion engine. You did ask for personal experiences in your title, in my case my 73 was run on a Mustang dyno where it put out 122 H.P. & 127 pound feet of torque using carbs off a 71 model. After I modified them i went back to the same dyno, same tester and achieved new numbers of 149 H.P. & 158 Tq. thats a gain of 22.1% H.P. & 24.4 on Tq. never touched the head! and I think those #s are a fair amount over stock. B T W my but dyno verifies the Mustang one. That has been a couple years ago and I have since removed the stock air horns and fabricated new ones a little shorter and wider with a much better entry radius. I also massaged the carb opening to match the new air horns. The car feels a bit stronger,maybe 5 H.P. or so ? I would now guess I'm in the 150-160 range. I would have to believe that if my motor was a fresh L28 that is 16% larger and better compression ( mine runs 155psi across all cyl. ) that 175-185 would not be out of the question. My own personal opinion/ experience is that major power improvements can be had in the Induction System.

[Tony D]

My stock L28 spun the dyno to 80hp with triple weber 40's, and header with 2.5" crush bent exhaust.

I removed and sold the webers, reinstalled stock EFI and stock cast iron manifold. Replaced the plug wires and did a general tune up of the engine.

 

That gave me 147HP to the rear wheels.

 

I removed all the 'performance' items and concentrated on TUNING not a 'magic bullet' and that is what you did WEB...

 

It's not the carburettors that gave you the power, it's the attention to detail and TUNING of what you had. Your power figures are middle of the pack and should be what is expected for a competently tuned STOCK engine.

 

If you want "MORE POWER THAN STOCK" you aren't going to get any appreciable gains with 'mindless bolt-ons'-whatever you install will have to be competently tuned as my example shows.

 

Webers, hey they're a bolt-on 20% increase.

 

No, they're not! And that is the POINT of my comments. He's looking for a 'magic bullet' and one doesn't exist. I got more from bone stock than a buttload of 'bolt ons' simply applied to the same engine.

 

Truth be told, the biggest pickup was spark plug wires.

 

There are no magic bullets. It takes work. Tuning is tuning as you say...but dispel the myth that you just bolt on something and you get "X" Horsepower---doesn't happen like that!

[WEBEZEEed]

Tony, AFC said he simply liked working on his car, thats great. I provided him with an option that if he wanted to put in a little time working on his S.U.s that he could see gains as I did. You are arguing with yourself, the only person talking about magic bullets and mindless bolt ons is you! You don't know me, we have never met,you don't know my Z, you don't have any idea what I can do or have done. So how is it that you can tell me what I done? Some how I don't think you are The Amazing Kreskin. It doesn't matter if you think my power levels are middle pack, so be it, it doesn't matter if it was 15 H.P. I think 20-25% is excellent for not spending any money save the cost of the book. I might guess that you have this book.The truth is my increases were 20-25% and the only difference....let me repeat...the only difference was the modifications to the S.U.s I didn't tune squat. All aspects of making sure the motor was in good running order were all ready in place. These are rear wheel # on a mustang dyno ( I've read other threads that hint of slightly lower readings on a mustang) on a 2.4 that now is over 200k miles and the head has never been off. My Z is nothing special and I'll bet that any other Z in good running order will respond likewise.

[AFCrain]

@WEBEZEEed~ I that may be just what I'm looking for. My father and I used to do those kinds of modifications to his/our race cars. I was only about 15 at the time so I didn't really pay attention to some of the things, well... actually a lot of them. While I appreciate the work and attention to detail with your carbs, I feel the same principles could be applied with similar results. That being said, I'm not going to be a nincompoop and buy the biggest carbs I can. I must say I'm a little vain as well. If I'm putting my own time and money into something, I would like to look as good as it runs, vice versa, whether it be a nice tuck job, custom one-off intake, etc... Thanks again for heads up on the book.

 

@TonyD~ It's obvious that you have 20, 30, 40 years more knowledge than I do, I have to that while I think I get where you're coming from, you really contradicted yourself with a few points and really got away from the main topic. I'm glad that you got 147hp to the wheels with an EFI, but I'm asking about personal experiences with different carbs, which you did provide in the your first post. Another thing; I fully understand that competent TUNING is required, I never said I was going to put a Holley 850 double pumper onto a stock engine and come back later asking "Why doesn't this work?" It's actually rather rude that you would assume I was only looking for a "magic bullet",who do you think I am, JFK?

 

I apologize for getting off topic and my original question still stands. What are your personal experiences with different carb setups?

[AFCrain]

@WEBEZEEed~ I that may be just what I'm looking for. My father and I used to do those kinds of modifications to his/our race cars. I was only about 15 at the time so I didn't really pay attention to some of the things, well... actually a lot of them. While I appreciate the work and attention to detail with your carbs, I feel the same principles could be applied with similar results. That being said, I'm not going to be a nincompoop and buy the biggest carbs I can. I must say I'm a little vain as well. If I'm putting my own time and money into something, I would like to look as good as it runs, vice versa, whether it be a nice tuck job, custom one-off intake, etc... Thanks again for heads up on the book.

 

@TonyD~ It's obvious that you have 20, 30, 40 years more knowledge than I do, I have to say that while I think I get where you're coming from, you really contradicted yourself with a few points and really got away from the main topic. I'm glad that you got 147hp to the wheels with an EFI, but I'm asking about personal experiences with different carbs, which you did provide in the your first post. Another thing; I fully understand that competent TUNING is required, I never said I was going to put a Holley 850 double pumper onto a stock engine and come back later asking "Why doesn't this work?" It's actually rather rude that you would assume I was only looking for a "magic bullet",who do you think I am, JFK?

 

I apologize for getting off topic and my original question still stands. What are your personal experiences with different carb setups?

[AFCrain]

Sorry about the double post. I'm not entirely sure what happened.

[frank280zx]

I guess he has his share of Carb experiance aswel

@Web Wel you did 'tune' your carbs I guess most over 30 year old cars might have some issues with wear and being slightly of tune by now, just a good overhaul and attention to detail work wonders. I think the roundtops a great carbs, but while over there id get some japanes tripples, they could be sold with a profit, And will ( when in right tune) do the same as you describe.

The Trick is dont go TO big stay with 40's on a L26 unless you really want to reuse them on another engine then get 48's orso and use the smalles venturi you can find. So you will have the power increase and the classic looks of tripples. Everybody has SU's

Also pay attention to details ( match your gaskets etc) when installing.

 

Do you just want to do Carbs or would you also be prepared to swap a cam? as if you do that with tripples you wil see allot more gains! Most stock cams drop off at 5K and there ispower to be made upto 6K with cast pistons.

 

Though depending on the general tune of you car now i would not hope for much more than 15 to 20 HP with carbs and maybe 30 HP with a cam.

 

Id say stay away from the 4 barrel but that is just my personal preffernece, further i have heard people complaining of leaning out number 5 or 6 with those, hence i feel that has to do with the head cooling issue discussed in a diffrent topic here.

Edited May 3, 2011 by frank280zx

[Tony D]

"Tony, AFC said he simply liked working on his car, thats great. I provided him with an option that if he wanted to put in a little time working on his S.U.s that he could see gains as I did."

 

I'm not arguing, I'm pointing out that changing NOTHING you got more power. Nothing bolted on, nothing changed. MY POINT EXACTLY!

 

Asking amazing kreskin? No, you asked for power bolt ons from carbs: There aren't any. Contradictions? No, I think not. You asked from what I can tell what you can CHANGE---'what carbs will give me more power'?

 

None of them.

 

 

TUNING is what will give you the power.

 

And hence: QUIT LOOKING FOR THE 'MAGIC BULLET'---that being defined as some item you 'bolt on' and get power from. They don't exist. TUNING is, has been, and always will be where power comes from.

 

Rather than wasting time looking for alternatives which you will then bolt-on and get some miraculous response from...consider the fact that simple competent tuning and spending time with what you got will return as much or MORE than anything you 'bolt on'...

 

My message has been the same and from what I can see clear and consistent.

 

That WEB wants to make is some personal affront to himself---that's his issue. Nothing of the sort coming from this end. Although if there are more things you did to your car, and are claiming it's only from your wonderous tuning---for shame! We can only know what you tell us, and your post makes it sound like you read a book, tuned, and were rewarded with power like you should have. Bravo.

 

Chances are good you did better than the PO of my prior car who took the EFI off, installed 40DCOE's on a cannon manifold, and headers and was rewarded with 80 some HP. WOO HOO! LETS HEAR IT FOR THE MAGIC BULLET BOLT-ON'S! Because everybody knows headers add 20%, and Webers add 20%, and the car came with 142, so that means 28HP (20%) for the headers=170, and 34HP (20% again) for the Webers means that car has 204HP now! Oh, wait, it's only giving me 80 at the rear wheels and struggles with a 17+ second 1/4 mile...there must be something wrong with the dyno, right?

 

Put it all back to the way it was, run consistent 15.50's in the 1/4, and Dyno to 147 in a 2695# Car....

 

Yeah, it was the bolt-ons that added the power. I just didn't realize they had to be UN-Bolted to get that power back!!!

 

Follow this yet, guys? No contradictions. No impugning of character or minimizing of achievements. Just an example showing that 'magic bullet bolt ons' AREN'T!

 

And from my read of your original post Crain---that seems to be what you are looking for...

 

My contention is, has, and will be that is not where you need to concentrate. TUNING is where you need to be. Nothing appreciable will come from CHANGING induction systems. TUNING what you have will give you more, at less cost (bang-for-the-buck I think was what was one of the criteria...)

 

Seriously, do you guys who are offended and thinking I'm arguing getting this yet? I'm not arguing, I'm explaining. Or did the criteria from the original post change and we are on a different track now????

[Tony D]

Oh, and to reinforce what I just said: PO took OFF EFI, put ON DCOE's in a 'bolt on fashion' and LOST power (like HALF TOTAL ENGINE OUTPUT) --- restored to a STOCK configuration and got 147.

 

This JIBES with WEB's comments that SU's are tunable to 140HP. Again, TUNED STOCK COMPONENTS. Now, WEB wants to play a semantics game in that thinking MODIFICATION OF CARBURETTORS is not a form of 'tuning'---I disagree. TUNING consists of modification of components so they are more suited to a particular application. Changing the timing advance or static timing is a TUNING tool. It is not a 'separate standalone modification'... it is all encompassed under TUNING. (I would think this would not be necessary to define, but whatever...)

 

The point being, either the stock EFI or the stock SU's are equivalent in power potential.

 

I have seen 192/196 HP at the wheels of SU'd cars. They had headwork and cams. They did NOTHING to their SU's other than possibly change a needle---again this being part of a TUNING process.

 

Let's remember what was stated and asked:

 

1)"I plan on slapping on a new carb setup on my L26."

 

2)"I'm looking for the biggest bang for my buck "

 

3)"I'm looking for input on power gains on carburated L series."

 

4)"Any input on the different setups is welcome, eg: SU's, triple webers, 4 barrel conversions, etc. "

 

Given those parameters the 'MAGIC BULLET' asked about in #4 is in DIRECT CONTRADICTION to the stated purpose given in #2.

 

The answer, given #2 is in there (even though later is was said 'cost is not a consideration' ) is that TUNING WHAT YOU GOT will give you THE MOST POWER with NO COST FOR HARDWARE.

 

To justify that, even if you got a set of DCOE's for 10,000 yen (what, in the day that was what they went for, now it's over $100) So lets say you got an HONEST 20% OVER what you got from PROPERLY TUNED SU's, you are looking at a cost of 0.65HP per dollar spent. While if you have (and likely you do) under or around 100HP now, and only spend time (no money) on TUNING the SU's and get to the same 147 starting point---you have a cost of ZERO DOLLARS per 47HP.

 

Seems to me this is a no brainer, but hopefully this explanation can make it a bit clearer what I'm saying.

 

I have given a firsthand example of bolting on carbs which lost power compared to stock. Even if they were tuned the most one could hope for was 165 versus 147-150. So 15HP for $100? Or 47HP for nothing. Or loosing 20HP for $100.

 

The choice is yours. Kids put too much emphasis on 'bolting things on the car to increase power' and that is just a cruel lie. It doesn't work like that. There is (as you hate to hear me say) no magic bullet.

 

Please don't get into the 'I can't see the forest through all the damn trees' attitude because I used EFI in my example and therefore you flush it. I have countless examples of idiots putting all sorts of carburetors on their engines in some quest for power as well... I just use that one because it's the most relevant today where people are looking (usually) to remove stock EFI for whatever reason thinking they will get some magic boost in HP with carbs, and without some competent tuning chances are damn good the NET RESULT WILL BE A POWER LOSS OVER THE COMPETENTLY TUNED STOCK SYSTEM THAT WAS REMOVED!

 

If you want ANOTHER example, I ran my 1975 Fairlady Z at Goya Tuning on Okinawa in 1988 with stock SU's and the L20A. The guys at Goya were hot to check out the engine because I spun their Bosch Eddy Current Dyno to 97PS... and the uncorrected power figure was over 100. This was comparable to most L28's that were coming in there with all sorts of 'power parts' on them. To think that my 2-Liter was making MORE horsepower than most L24's being driven around in 240's stateside was kind of a shock. This has been reinforced by countless attendances at Dyno Days in So Cal and worldwide where guys with stock Z-Cars, 240K's, Skylines, Leopards, 810's and the gamut of cars come in off the street and check their power point and get shocked. It really is amazing how poorly most cars are tuned. And really scary how low relative power output is even when tuned to 'stock' specifications. At the time, that car was the bane of the Squadron---bone stock and FAST. But as I have mentioned on many occasions, an ITS car is also 'stock' using all the same components. The difference is tuning, not changing to the latest go-fast goody.

 

It's always shocking to me knowing how much power a PROPERLY TUNED L-Series can make...and then the almost UNIVERSAL comment after someone spins a low number on a dyno: "Man, I need to get me a set of triples!"

 

Sure, spin 100 with the SU's, then put those triples and see 120...or maybe 130. Wow! But realizing that the stock stuff will give you 147????? Does that mean you HAVE to change to some 'magic bullet' component to get more power? To my way of thinking, that guy who spun 100, and then got 130 after paying big money and switching to a tuned set of 40's is down on power by 35HP! He SHOULD have had 140-145, and after triples 160-165! But he started at 100, and now has 130, and wonders why a 'stock' Fairlady Z with an L20A and baby SU's spanks his butt every time they line up at the track. (Perhaps you stand next to my open engine bay swearing in foul language after being beaten for the 14th time that night in your hot coupe--just swearing and cursing me because you can't beat me and there 'must be a cam in that engine!' Because you spent lots of money for bolt on power gains and ARE STILL SLOWER than this 'stock' car!!! Actual example of what happened to me at the Houston ZCON Drag Night!!!)Power gain is relative--have a poor starting platform and sure you will gain power. But it may still be BELOW what it SHOULD be with a proper starting point!!!

 

Unfortunately WEB and I AGREE that you DON'T have to do that, he just wanted to be offended by a post that was AGREEING with his comments and didn't 'get' that.

 

Hopefully you do now as well---don't read things in that aren't there, as you are stating re: 850 holleys, and humongo carbs. This comes from your own insecurity, and you aren't understanding the simple, frank answer you are getting from me is not rude, and it's not insulting. It's just stating facts. You asked a question, you got an unpolished direct answer. That is what I do, that is what I'm paid to do. Now, you want to pay me $150 an hour I can write you a detailed white-paper on the subject and can deliver it via e-mail. But you're not paying me, so you get the free version stripped of language meant to soothe an angry customer who realized he just spent $4000 for an induction system that gave him the same HP that his OEM setup was capable of, wasting colossal time (and money.)

Edited May 4, 2011 by Tony D