Throttle Body Question (street/strip 347sbf)

[C.Anderson]

Hello everyone!

My name is Cris. I'm new to the forum, but have been interested in Megasquirt for many years. It's such an incredibly cool concept.

Anyhow, I own a 67 Mustang. The car has been updated with an 11:1 compression 347, 225cc Highport cylinder heads, solid roller cam, 5spd transmission, and 4.11 gears (soon to be 4.56). I currently run a 700dp Holley carb (yes, its quite small for the application, but its what I had on hand). Exhaust consists of 2" primary tube headers, with 3.5" collectors, connected to roughly 6' of 3.5" exhaust pipe per side, along with two 3.5" Dynomax Race Bullet mufflers per side. All that being said, the car is/was a daily driver. You can see more of the car at:

http://www.youtube.com/peteandersonracing

Or:

http://www.cardomain.com/ride/3339324/1967-ford-mustang

So, my predicament is that I'm looking to switch to fuel injection. This particular 700 Holley is on its last leg, and rather than drop $800+ on a good custom carb, I go I'm really considering a throttle body injection, as I'm on a strict budget, and need to get the car running again ASAP. Additionally, I may end up driving 40 miles one way to work here shortly, making the injection even more attractive. If I can get into port injection for a similar price though, I'd consider going that route as well.

As for what I've researched (recently) so far, I spent a lot of time on the DIYAutoTune site this morning. I've never done any electrical work in terms of circuit boards and such, so the $747 complete carb to tbi kit caught my eye. I found a site called Auto-Nomics that offers a 4 injectors, 750cfm throttle body for $399, equipped with a gm tps, and ready for a gm iac. Another option was finding a way to adapt the GM 850cfm throttle bodies I keep finding on eBay to my system. They're only $200 or so, and might be a viable option if they'll work. They do say they only support 500hp/tq, but I'm hoping an injectors upgrade can help with that. This car has gone 125mph in the 1/4 mile, short shifting, with only 32* timing, and that little 700cfm carb. With everything setup properly, it should be making 580ish horsepower.

Anyhow, does anyone have any throttle body suggestions? I'd also gladly accept any advice on how to being the overall price down . I'm really looking forward to diving into EFI, but knowing for sure where to start has been a bit frustrating lol!

Cris

[C.Anderson]

By the way, please forgive any typos, spelling errors, or poor grammar. My current internet is a phone, and auto correct plays havoc with forum posting!

[Matt Cramer]

We just wrapped up a dyno session on a Camaro with a built 383 TBI motor - it was using a similar modded TBI setup. Had to stop tuning at 4,000 RPM and 250 hp to the wheels because the 80 lb/hr injectors were running out of fuel. I wouldn't recommend a single two barrel throttle body here. At your power levels, a two injector setup is going to need 170 lb/hr injectors, and I'm not aware of anything in that size that is meant to work in a TBI.

We've also found that throttle body injection setups that put the injectors below the throttle blades almost always suffer from significant fuel distribution issues, particularly at low throttle. If I were going to use a TBI setup on a seriously built motor, I would either use two TBIs on a dual quad manifold, or get a used Holley Pro-Jection four barrel throttle body with ~90 lb/hr injectors. These are a pretty decent design, something of an outgrowth of the Mopar TBI motors in the late '80s. We tried one on our Nova, but it didn't get any more power. Concluded it was a case of right mod, wrong engine, and the smog 350 just wasn't pulling in enough air to benefit from the extra two barrels. Your motor is more like what this was meant for.

[sheriff]

i completely agree with matt. i tried a 670cfm holley two bbl on my dodge 440 that been rebuilt to a higher compression and some head work. it would run out of steam under full throttle. i have since built a 496 stroker, roller cam, hyd roller lifters and roller rockers. i converted an alum intake for port injectors (8x42#). i found a used 900 cfm holley throttle body on ebay for a good price. the engine runs great. you should be able to source a port injector manifold somewhere. my next step is to go with the sequencer setup. good luck jimk

[C.Anderson]

Thanks guys! I very much appreciate the responses. I tried the search function repeatedly yesterday, but its difficult to quantify my question in such a way that the search function gives valid responses. I finally resorted to a page by page scan of this forum, and the fuel forum (this probably should have gone there lol). After about 20 pages on each forum, I'd gathered this was going to be the case.

So, since I can't find any higher cfm Holley style pieces on eBay...it looks like I'll either be going the Pro Comp route with the combined manifold and 1000cfm tb, grab a 255lph pump and regulator, and looking for some used rails and 42lb injectors. The biggest expense is still the Megasquirt, and I'll still have a bit more reading to do there. I'm really unsure whether to build my own or buy a completed unit. I'm a pretty handy guy lol, but I'm unsure what tools will be necessary, and whether the cost of those tools will very much offset the extra cost of a completed setup.

Anyhow, thanks again guys...I'm off to search which Megasquirt will be my best option, as well as whether I can do port injection (batch or sefi), and still control the spark with the distributor for the time being. Matt, you'll be hearing from me sooner or later. I definitely am the kind of guy that supports those that freely support others .

Cris

[fury fan]

So, my predicament is that I'm looking to switch to fuel injection. This particular 700 Holley is on its last leg, and rather than drop $800+ on a good custom carb, I go I'm really considering a throttle body injection, as I'm on a strict budget, and need to get the car running again ASAP. Additionally, I may end up driving 40 miles one way to work here shortly, making the injection even more attractive. If I can get into port injection for a similar price though, I'd consider going that route as well.

Those sentences jumped out at me. You have an uphill battle. Budget, ASAP, daily driver and 500+ hp don’t mix well for a first-timer’s jump into EFI. Can you find a beater econobox to drive meanwhile, or can you throw a stock 5.0 in for short-term whilst you plan for the 347?

EFI isn't cheap, even when it's DIY. A good fuel pump will be $125+, you’ll spend $100 on lines and fittings, $40+ for a good filter, etc. We haven’t even gotten to injectors or TBs/intake required for 500+ hp. You better plan on $1000+ at least to convert your car ($1500-2000 is more realistic).

As for what I've researched (recently) so far, I spent a lot of time on the DIYAutoTune site this morning. I've never done any electrical work in terms of circuit boards and such, so the $747 complete carb to tbi kit caught my eye. I found a site called Auto-Nomics that offers a 4 injectors, 750cfm throttle body for $399, equipped with a gm tps, and ready for a gm iac. Another option was finding a way to adapt the GM 850cfm throttle bodies I keep finding on eBay to my system. They're only $200 or so, and might be a viable option if they'll work. They do say they only support 500hp/tq, but I'm hoping an injectors upgrade can help with that. This car has gone 125mph in the 1/4 mile, short shifting, with only 32* timing, and that little 700cfm carb. With everything setup properly, it should be making 580ish horsepower.

A 454 TBI would be right on the edge for you IMHO, and as already mentioned 2 350 TBIs on a DQ manifold might be a better route. If you get a 454 TBI unit, be aware that the ‘early’ ones have 90lb injectors run at 13 psi, while ‘later’ TBs run lower-rated injectors at 30 psi. The ultimate combo is early injectors and a later 30lb spring, which might get around 500 hp with a modified TB housing/blades.

Be aware that the 454 TBI requires a spreadbore intake and adapter plate, the bore spacing is too wide for a standard square Holley-style flange. Even if you have a bigger plenum, you still need an adapter plate, and they run $50 @ Summit. I’ve made some of my own adapter plates, and I can tell you that $50 is pretty cheap unless you have a machine shop at your disposal. I’ll never make one again -- and I’m a tightwad…

IMHO, avoid the Autonomics TB, that is ancient technology (it’s from the early 80s) and doesn’t have the benefit of OEM development the GM TBI stuff had. It was originially marketed for RVs.

I'm not an EFI expert, heck I don't even have an MS runnig on anything yet. However, I have spent 4+ years reasearching, reading, JY-ing, home-fabbing intake manifolds, and preparing for MS. I've learned firsthand all the little hardware details that an EFI conversion might require -- and the options. I've made quite a few posts on the GM TBs over the years, too - search.php?author_id=18225&sr=posts

[C.Anderson]

Thanks FuryFan! That post answered a couple specific questions I had regarding the GM factory stuff.

As for my car, I should probably clarify a couple things that it seems I skipped over (or inadvertently misrepresented).

First, the current fuel system consists ENTIRELY of 300PSI pushlock hose. Any fittings are AN fittings and rated for methanol. My tank is sumped, with -12an on both the feed and return. The return is currently reduced down to -8an for the bypass on the Mallory Comp 250 pump. This pump will actually push 23psi, and so might be an option for an early style throttle body...though I don't intend to go that way. The fuel line from pump, to the engine compartment is -12, reducing down to -8 for the carb feeds. Current filters are a Mallory Comp 500 40mic pre pump, and a -12an, 10" long 10mic circle track filter before the engine cimpartment. Here's a couple pictures:





Basically, when I setup the fuel system...the plan was to allow for either E85, EFI, or even possibly both on the future, thus the psi rating, corrosion resistance, and sizing of the system. A Walbro 255lph pump (with a second in tandem for E85 possibly down the road), mounting kit, proper regulator, and a few fittings for the splice should cover the fuel system.

Second, the current intake is a square bore Victor Jr (unlikely for fitment of the 454 throttle body, as you clarified above). Above I mentioned a Pro Comp 1000cfm throttle body, ready for a GM tps and iac, coupled with their already drilled Victor Jr style single plane intake for $399 shipped. This may be the route I have to take, if I can't find a used 950cfm Holley tbi.

Third, the car IS a daily driver, but hasn't been running in a year due to parts related valvetrain failure (dont get me started, those poc Comp Cams Ultra Gold rocker arms cost me a $400 cam, and $2500 Jesel lifters...no typo). The ASAP is because I miss my car, and have a bit of extra money coming in for taxes, both for the repair, and to help a bit with the EFI upgrade. It won't cover all of it, but it'll help. Additionally my wife is wanting to go back to work, and while we have a vehicle to get us by for now, she can't until I put the Mustang back together. So, while there is a hurry, there's no real rush .

Anyhow, thanks again guys for the awesome replies. In reading my initial posts, I see where the confusion came in. It's tough to properly preview your posts before submitting them when you're using a phone to post lol!

Cris

[kjones6039]

We just wrapped up a dyno session on a Camaro with a built 383 TBI motor - it was using a similar modded TBI setup. Had to stop tuning at 4,000 RPM and 250 hp to the wheels because the 80 lb/hr injectors were running out of fuel. I wouldn't recommend a single two barrel throttle body here. At your power levels, a two injector setup is going to need 170 lb/hr injectors, and I'm not aware of anything in that size that is meant to work in a TBI.

Yikes.........

You're making me nervous guys!

I have about $5000 in this 383 and you're telling me that 250 hp is all I can get from 900 cfm w/ 4-85# injectors?

Man, she's gonna kill me if I ask for MORE $$$$!

Seriously am I in trouble here? So far the car seems to perform well.

Ken

[C.Anderson]

Hey Ken!

I believe in the quote you posted they were discussing a two injector factory GM throttle body. I think with 950cfm and four properly sized injectors, you'll be safe.



Cris

[kjones6039]

Thanks Cris!

Thank goodness!! I was starting to pack my things when your post came in.....

Sorry, I missed the 2 bbl thing....

Ken

[fury fan]

Cris –
Based on your updated info, you’re in a better position than I had presumed.

For the amount of work you have done to your car, I’d recommend you head down the port-EFI path ILO TB EFI. Nothing wrong with TB, but I’m thinking for the level of work you’ve already done and the performance you have, you’ll be cheaper in the long run to put better hardware in it. More likely to not hit constraints on the dyno as in the other story in this thread.

I also presume you have no heat crossover from heads to intake, and TBI would benefit from some heat due to it still being a wetflow intake. I also presume you have a stout cam, and port might give better idle quality than TB. Just my speculation, though. Your cam probably has more .050 duration than mine have at 0.0”!

[C.Anderson]

I think you're right on the port vs tbi thing. I just figured if the megasquirt would run both, the tbi would be the simplest swap, and would be a nice baby step out of the world of carb lol. Guess its time to forget dipping my toes as you say eh?

Lol .

As for idle quality, its only a concern in terms of crispness, and that it is stable (no creeping/surging). The idle is set to 1100ish regardless, in order to keep oil on the springs and lifters. The cam that's in it now (.634"/.634", 248/266@.050") would idle contentedly at 850rpm...but the springs build heat fast when you've got 750lbs over the nose lol. The new cam is a bit larger (.704"/.672", 260/268@.050"), and will likely require that 1100rpm to stay running lol. Funny thing is its much less aggressive than the old cam, and requires less spring, even up to the new 8700rpm redline. I think, altogether, the new setup will be much happier than the old lol .

Also, an update! Years ago, I had a Canfield single plane intake. The interesting thing about this intake is, it was designed strictly for airflow...meaning NO wetflow. Additionally, it makes a Victor Jr look small lol. I sold it to a young man, and have regretted it ever since. Well, the news us, I got hold of him, and might have a chance of picking it back up. If I can...this EFI thing is going to be an interesting deal lol. With that manifold, my heads will flow over 340cfm, as a conservative estimate .

[fury fan]

The cam that's in it now (.634"/.634", 248/266@.050") would idle contentedly at 850rpm...but the springs build heat fast when you've got 750lbs over the nose lol. The new cam is a bit larger (.704"/.672", 260/268@.050")...

I was right, those cams @.050" are comparable to what I have @.000"!

Your engine is way above my league -- I won't be able to offer much tuning/configuring advice, but I'll answer any hardware questions if I can.

[C.Anderson]

The cam that's in it now (.634"/.634", 248/266@.050") would idle contentedly at 850rpm...but the springs build heat fast when you've got 750lbs over the nose lol. The new cam is a bit larger (.704"/.672", 260/268@.050")...

I was right, those cams @.050" are comparable to what I have @.000"!

Your engine is way above my league -- I won't be able to offer much tuning/configuring advice, but I'll answer any hardware questions if I can.

Well, you guys have been a huge help already . If I can get my hands back on that intake, we'll all be in for some fun lol.

[C.Anderson]

Well...I'm not sure how to say this...but things got...hmm, how to put it?

Let's just say the volume got turned up to 10.

I was doing some searching on Racingjunk...and came across a rather...odd ad. I called the seller, we talked for three hours lol, and I'm now the proud new owner of a sheetmetal EFI manifold. But wait! There's more! With that manifold came a pair of 270cc, 400+cfm cylinder heads . Also included are the proper Jesel shaft rockers, and fabbed valve covers.

So, my next question is...how does Megasquirt play with 03 Cobra throttle bodies? I think the Lincoln stuff would work as well...but until I have the manifold in my hand...I won't know. Do you guys have any idea what those throttle bodies flow so I know how many I'll need to feed 600-650hp n/a?

By the way fury fan...I blame you! I took your signature to heart I guess lol. Talk about jumping in with both feet lol! Here's a couple pictures of the manifold:











And the style throttle body I believe it takes:



Boy oh boy...is this going to be a steep learning curve!

Cris

[Matt Cramer]

Nice score! As long as you're using a cable operated throttle body, I don't anticipate any problem.

[fury fan]

You're gonna need a hoodscoop, friend!

FWIW, I think those injector bungs are in a bad location, at least for a street car spending any time at lower RPM. The injector should be aimed more vertically and point down the runner, preferably into the intake port, and ideally at the intake valve (although that’s not always possible). These bungs might be OK for an engine that spends all its time at high RPM with few throttle transitions, which is apparently what an intake like this is designed for.

An intake like this one will also not have a lot of heat in it (compared to a cast intake, at least) so you won’t have hot runner walls to help atomize the fuel. You’ll surely need to delve into alpha-n tuning for this one (alpha-n tuning involves consideration of the fuel stuck to runner walls that peels off with airflow).

At a minimum, you should use ‘fogging’ injectors that atomize the fuel as much as possible. If you look thru my recent posts I put a link to a photo that describes this. I think it’s on Witchhunter’s website.

I don’t know specifically on your TB airflow question, but a 4.6 Lincoln Mark 8 engine was typically rated at 280hp, so 2 of those TBs should be in your ballpark. Here’s a link that helps you calculate based on bore size. http://www.megamanual.com/v22manual/minj.htm#throttle

[C.Anderson]

Hey Fury Fan,

I did a little research. The Cobra version pictured goes 1300cfm...and while I couldn't find numbers for a Lincoln, I'd assume something over half that. So as you said, I think two would work perfectly with this motor. Once I build the 377" motor in the future, two Cobras will be perfect.

I hadn't considered the compatibility of the intake with street use. The nice thing is that once I start my new job I have access to people/tools capable of fabricating a new one, with more street oriented principles. I never would have considered making one from scratch, but with this one as a guide, I'd be comfortable with modifying the design. For example, I don't need six throttle bodies. I could lose that outer plenum area, allowing me to realign the injectors. Either way, ill be building my own fuel rails lol. Years ago there was a guy that sold bulk rail, and the cutter for the injectors seat. I'll have to see if I can find him again.

I'll definitely try to find your post on those injectors...they sound like something I would need regardless.

Cris

[C.Anderson]

Nice score! As long as you're using a cable operated throttle body, I don't anticipate any problem.

Yeah, my car is already converted to cable, so that makes it a bit easier. I'm a little unsure of the logistics I'll need for multiple throttle bodies lol...but I'm sure it'll be more apparent once everything is in the car.

Sure would have been easier if they'd mounted them perpendicular to the engine centerline lol...but hey, then they couldn't have fit SIX of those tiny little 1300cfm throttle bodies, right?!

Cris

[C.Anderson]

Hey guys!

Small update. The parts have all shipped finally. I should have everything in hand by next week except one head which I had sent to my cylinder head guy to be flowed.

Anyhow...here's where things stand. This setup is somewhat historical apparently. There was only ten sets made. I had quite a long discussion with Rick Smith, founder of TrickFlow, and designer of these heads. 400cfm is about right for the flow. He gave me some ideas on how to make them run harder as well. I will still be using them of course, and the intake for now. This leads me to my next question though. I have the ability to easily make new top plates for this manifold, with a minimum of expense and effort. In order to get the car moving under its own power as quickly (meaning cost effectively) as possible, what would you recommend? The plenum of this manifold is very interesting. With proper placement and/or temporary foam baffling, it appears I could run anything from two 500cfm 2bbl carbs, to two GM tbi setups...to four single bbl tbi setups situated directly over each pairing of intake ports. Distribution shouldn't be an issue with the curvature of the lower portion of the plenum, and the variety of placement options allowed by the wide flat top plate. Any of these options should negate the issues caused by the 90* placement of those injector bungs.

So what do you guys think? I'll need 1000cfm or so (4bbl rating), and matching fuel flow. I kind of like the idea of four single squirters...but don't know how cost effective those would be, or even what models to look at. Smaller sizing for hood clearance would be nice too lol, but that is what it is. Two GM tbi rigs would provide enough air and fuel I think...but the feasibility or overall cost effectiveness is beyond my limited experience.

So...to break the issues down in order of seriousness:

Fuel distribution
Megasquirt compatibility
Overall airflow
Cost
Fitment

And, the main tool I have at my disposal to combat these issues is the interchangeable top plate that allows virtually unlimited placement options. Also contributing to the positive side is the unique (to small block fords) port placement, lower plenum design, and ease of baffling the plenum.

So how about it guys? Feel like helping me come up with a cool, possibly unique, yet cost effective solution?

Cris