Webers or injection?

[Dean Lampe]

I feel like I should be getting a little more out of my engine. I know we have discuss Weber's on larger engines and their limited capabilities. I have been seriously looking at TWM and Dynatek for a change. I would love to talk to someone who has made the change or someone who is familiar with either system.

I just don't seem to be pulling as hard as I think I should out of the corners and down the straights. I am running 48IDA's with 40mm chokes. I have 45mm chokes on the shelf. Should I just keep tuning the Weber's or go with the injection? How hard is it to set this stuff up? Any horror stories?

I just need some advice.

[Bill Musarra]

Dean,
I haven't fired mine up yet(351 Windsor TWM 50mm), but unless you are into tuning, I would go with the injectors. They are a computer driven setup that is laptop tunable to get the performance you want. The ignition is your choice, but it is all laid out in front of you with pretty pictures and all. Once you get it the way you want, it is set it and forget it. Most cars today are injection setups. I don't think many ever have to be tinkered with. You can even have different settings for the street and the track, allowing you to drive to the track, adjust the tuning and run. I believe my system is a F.A.S.T. setup and distributor less(they have electronic distributors as well). I haven't seen it in several months. It is at the engine builders shop. It is setup for installation next week or two. One of the things you have to get right is the size of the injectors. You probably will have to go with 36-42# injectors. You will also have to change out your fuel pump(s) also. You can go to their web site to check it out. I don't mind working with the webers, but I would rather be driving than tuning. You won't have to worry about the backfiring thing either.Here are some articles:

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Web site:

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Bill

[Rick]

Dean: Pulling out of the corners and accelerating down the straights is a function of Torque. Without attempting to change your ideas, is it possible that the larger venturis (while in search of top end HP) have softened up the torque curve and made it not quite as responsive as you would like?

[Jac Mac]

Dean,
Right back at the beginning when you were crying croc tears about your setup I gave you jetting from a Boss 302 which was based on 45mm chokes. That assumed that the RPM would be kept between 5000/7500. Since you have around 370 cu in and Yates heads you should be able to run between 4500/7500 with a similar setup. That 302 cube motor was fitted in a 70 Boss Mustang circuit car & at the top of its category at the time. Now you come along with 370+ cubes and are trying to tell me you are getting anything like maximum performance on 40mm chokes , hell your intake valves are 50mm+ in dia.
If you really want a proper baseline on which to judge your cars performance eat some humble pie & fit the original 4bbl manifold the motor came with along with a road course carb & Air Cleaner and try that.
One other thing- neither chassis or rolling road dynos can give you all the answers when you start running up around 150+ mph, thats when airflow quality & temp into the engine bay and carbs etc really starts to play tricks on you.

[chuck smith]

Dean, that new BOSS Holley look EFI that I think Dynatek is now selling my answer some of your issues. It has a large throttle body like a big Holley but you do lose the Weber look.

New Product Blog » RetroTek Boss EFI System

[EGLITOM]

Originally Posted by Rick

Dean: Pulling out of the corners and accelerating down the straights is a function of Torque. Without attempting to change your ideas, is it possible that the larger venturis (while in search of top end HP) have softened up the torque curve and made it not quite as responsive as you would like?

Rick
i heard this engine reving. this thing responds like nothing i heard before ( beside a top fuel dragster in the pits at the test run after refitting the engine, they just explode).
Saying this , the engine was cold at this stage and still responded like hell.
Dean thinking about this, this supports Jac Mac assumption. Probably chokes to small and jetting a bit to rich.
Are you running a wide band air/fuel sensor to tell you during your sessions where your jetting is.

THe quick response of your engine is amazing, but i think it is due to the very light rotating assembly and it will still be there with the 4bbl carb.
Less costy , less hassle, more power. go Jac Macs route

BTW: too much is never enough ?

TOM

TOM

[J. Salmon]

You'll have to give me a few months, but I am going with the Kinsler manifold and FAST EFI. You have much more experience than me, but when we went from an easy to tune Edlebrock carb to the EFI (Massflo) on our Cobra, it was NIGHT and DAY. I have no dyno numbers, but the smoothness and predictability of the EFI system is just worlds apart. Instant and measured throttle response, so much easier to modulate than the carb. It runs much beter at cruise, but it runs better at WOT too.

Personally, I think the Massflo system (with Mass air flow sensor) is probably the best working system out there, better than the speed-density systems like what I will be using. I just couldn't give up the look.

[Dean Lampe]

From Jac Mac......

380 cu in =778.38cc per cyl . Therefore;

Idle jet.............. 70 to 75
Idle jet holder..... your 120 should be Ok given that you will be increasing jet size.

Now you get to the main circuit- You have to get real honest about which category you would put yourself in here- Hi Perf Road or Competition. In your case I would suggest that you might have to consider having two jetting setups for your car especially if you intend comp use due to the extremely strong signal that motor is going to give the carb when you start to explore the upper RPM range.

Choke size.........42mm Road-45mm Comp
Main Jet............170 Road---180 Comp
Air Corrector.............On the Road application around 200 thru 220 air- for Comp air should be smaller than main jet by around 50/60 eg 110/120 Air.
Emulsion tube.......Keep the F16 for Road but try F7 for Comp
Pump exh .........50

Finally I must remind you to be real careful particularly in regard to full power runs in the higher gears particularly with the larger air correctors you currently have installed, a hi speed leanout is very likely under these conditions with all the tears ( real ones ) that will accompany it. Those 40mm chokes on a large cube motor only increase the risk factor. I am sure it feels nice & responsive now in short bursts of acceleration, but when you really start to get serious they will cause some problems. looking at your engine specs you have a race engine- not street engine, treat and tune it accordingly; ie dont spend any more time than you have to under 3000 rpm.


I am going to switch everything to your comp setup and see how it runs. That would mean switching to 45mm chokes and coming WAY down on my 210 air correctors. Does that sound good?

[Jac Mac]

It is going to need a combo like that to put it in the ballpark. The thing you have in your favour is the Yates heads intake ports have slightly smaller cross section area than the Boss 302 which should help a lot at around 4500 rpm. ( the Boss motor used to literally 'fall' off the shelf below 4000 ).

As I noted in that earlier data, this is not going to be a 'street' type setup- RPM will have to be kept above 4000- keep a close eye on whatever mixture monitoring equipment you have on board & resist the temptation to do one more lap to see if it gets better [It very seldom does ].
If your running leaded race gas find a guy who has crewed on race cars & knows how to read plugs to help you out for the first full power runs, you should do this on a private type track test where there is no pressure to please a crowd or some other third party.

[Big-Foot]

I'd be interested in what Jac would think for a baseline jetting for the same setup (48 IDA - 37mm Chokes) on a 331 with a max RPM of 6500...

She's going to the Engine Dyno on Tuesday...

Cam is the new Inglese designed cam made specifically for this carb setup;
222 - 224 Duration
.571 Intake
.565 Exhaust

115 LC (Should idle like a pussy cat)

Webers have out of the box jetting from Redline;

Currently has F7/135 - 120 - 120

-edit- Idle jet? 70F10 in a 120 holder

I'll be honest - I've not tuned an IDA before..

I've done DGV, DMTR, a long time ago I worked on the DCOEs

[Dean Lampe]

Do you have an opinion on stack type air density Fuel injection? I hear as many war stories about tuning FI as I do webers.

[MReid]

Dean, I'll give you my opinion. I was running Wayne's Very Cool Parts EFI stacks on a 392 Ford crate engine (430 HP advertised) in my coupe. It is a speed density system that has a common vacuum plenum in the manifold that feeds the sensor in the computer. The ECU was a Redline 882 system that controlled both fuel and spark. The fuel map is vacuum over RPM and has an infinite amount of tunability. It even has the ability to vary the ratio of fuel enrichment over the rpm curve driven by TPS vs. the fuel map. This allows you to tune for the typical challenges that a stack style SD set up has where you are at high rpm with the throttle plates open and you suddenly brake, snapping the throttle plates closed and low rpm with the throttle plates closed and you floor it. Anyway, the amount of options and flexibility of the system can be daunting. My at the time 13 yo son and I drove the car around for many, many hours with the wideband connected and the ecu in open loop, fine tuning the fuel curve on the laptop and got it pretty well set. It was phenominal at low to mid-range with wonderful throttle response. It wasn't as potent on the top end. I never had it on a dyno, but judging by seat of the pants and experience this was the case.

Now the reason I know this is that one day the car started running like crap. I hooked up the wideband and the afr was jumping all over the place 5:1 to 20:1 with no apparent reason. I spent days troubleshooting it and finally one weekend in a fit of frustration, removed it and installed a single plane manifold and Holley 750DP. I can tune a Holley carb and we had it running great in a few hours. It didn't have the same excellent throttle response the stacks had, but at wot over about 2500 rpm, it was unbeatable.

Okay, a long story, but one of the things I liked about the Redline ECU was that the tunning parameters and controls were very similar to tunning a carb. It had an acceleration circuit that you could control amount, duration , and sensitivity. The fuel map was the same as jets on a carb, but it was as if you could control the size at every rpm and manifold pressure. It had additional controls to compensate for outside temperature, coolant temperature, and altitude. The biggest issue I had with it once I got used to how it worked and how to tune it was the complexity and difficulty of troubleshooting when something went wrong.

I hope that is helpful!

[Jack]

Well, I had webers and sold them to Randy as they would not clear the deck lid on my Mk1 and there was not any room for the air cleaners even if they did fit. I went with EFI TWM throttle bodies with 45 lb per hour injectors on my aluminum block 427. This is not my first rodeo with EFI so tuning was not bad. With speed density EFI and any engine with a cam the manifold pressure jumps around, with Electromotive EFI they have a blend funtion which you blend MAP sensor with the TPS sensor which is a pretty stable output at engine no load conditions which enables you to have a stable EGO signal at now load conditions (cruise or idle). I don't have a problem with webers at all and most of the Ferraris I have had had webers, seldom did I have or problems with them BUT with EFI you can change any parameter with a touch of the keyboard which gives you a presice tuned engine. Just my opinion. I love webers and EFI.