Can someone tell me that. How small is this thing? Will a well tuned Tempo TBI make more power or less power than a well tuned Weber 38/38?
throttle plate & injector size on Tempo TBI?
- Thread starter falcon fanatic
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Okay, then the logical follow up is is there an injector that will flow sufficient fuel to handle a 200hp motor (which is more than mine will make probably ever)?
I can get you the diameter of the opening in a little bit (the engine is hot right now), but as for the tempo tbi supplying 200hp, no it will not. From my time with it, it will supply a stock 200ci, or a 200ci with some slight work, no more.
The Green top injector is rated at 700cc's @ 12.5 psi (its been a wile since ive needed to know this, might be wrong) you can use some calculators on Megasquirts info page to see what increasing the psi can do.
http://www.megamanual.com/v22manual/minj.htm
Also, i am running at 15psi right now. I am getting ~2.0ms pulse width at hot idle. I have not tested up to super high rpm, but i found the slope of two data points of a recording i made a wile ago, and if i remember correctly the injector would go %100 duty cycle at around 5600rpm. I have not had it past 4500rpm so a mathematical estimate is all i can give you.
And i dont know of any other injector that will fit.
The Green top injector is rated at 700cc's @ 12.5 psi (its been a wile since ive needed to know this, might be wrong) you can use some calculators on Megasquirts info page to see what increasing the psi can do.
http://www.megamanual.com/v22manual/minj.htm
Also, i am running at 15psi right now. I am getting ~2.0ms pulse width at hot idle. I have not tested up to super high rpm, but i found the slope of two data points of a recording i made a wile ago, and if i remember correctly the injector would go %100 duty cycle at around 5600rpm. I have not had it past 4500rpm so a mathematical estimate is all i can give you.
And i dont know of any other injector that will fit.
I have read that most TBI style injectors start having issues around 20 psi. In theory around 150 hp is about all you are going to get out of any single injector. Once you get above about 35 lbhr they start getting expensive. Over 50 lbhr are kinda rare and even more money. The GM tbi's are by far the most common ones out there. Most of them are around 60 lbhr IIRC.
The tempo (like most TBI's) use a side flow injector. Fitting a more common bosh style would be a lot of work, I think you would be better to just start over. There is or was a guy or company making a thing that looked like a 50's rochester with a single bore and to injectors hidden under what was the bowl.
The tempo (like most TBI's) use a side flow injector. Fitting a more common bosh style would be a lot of work, I think you would be better to just start over. There is or was a guy or company making a thing that looked like a 50's rochester with a single bore and to injectors hidden under what was the bowl.
So, Moe, as far as you know, the green top is the biggest one available for this unit. What car is that originally from? Oh yeah, excellent link. I've been working my way through the megasquirt manual, but there is a lot htere to digest.
Right now my engine has a totally stock bottom end with a fairly modified log head, headers, etc. It probably makes nowhere near 150 HP, so I'd likely be fine with this tempo unit. I have a GM TBI as well, but right now I'm looking for the easiest assembly possible. Once I have the MS built and wired in and the fuel system all set up and have it tuned and running, I could always upgrade to the GM unit if it became necessary. That's probably a camshaft and lower end rebuild away, though.
Fordconvert, I've seen the unit you are talking about. the beauty of the Tempo unit is the price and ease of installation. If I need more umph I'll go with a GM unit ( or dual extrudabodies if I'm feeling rich)
8) 8)
Right now my engine has a totally stock bottom end with a fairly modified log head, headers, etc. It probably makes nowhere near 150 HP, so I'd likely be fine with this tempo unit. I have a GM TBI as well, but right now I'm looking for the easiest assembly possible. Once I have the MS built and wired in and the fuel system all set up and have it tuned and running, I could always upgrade to the GM unit if it became necessary. That's probably a camshaft and lower end rebuild away, though.
Fordconvert, I've seen the unit you are talking about. the beauty of the Tempo unit is the price and ease of installation. If I need more umph I'll go with a GM unit ( or dual extrudabodies if I'm feeling rich)
8) 8)
fordconvert":2a88kl3l said:
You'd be right. We had trouble in the low teens and ended up running at 10 psi for a carb conversion of a jap motor.
I don't think I'd bother with TBI again, brazing some bosses on the intake manifold to take normal fuel injectors is pretty easy.
fordconvert":1n6xwslo said:
GM TBI injectors max out at, IIRC, 90 lb/hr.
Which x2 is good for about 300 hp in an engine with a sensible compression ratio.
Large injectors are readily available, that is not the problem. The problem is that large injectors suffer from a lack of resolution at the low end, leading to min pulse width issues at idle.
Everything is available if you have enough money.
The 90's only came in the early 454 trucks. In my area they rarely turn up. The 2.8 were 33, 4.3 were 45. 5.0 were 40. 5.7 55. Later 454's were 80. The HO 5.7's were 65. Multiport takes more fabrication but especially now days there are lots more options for bosh style injectors which ultimately tends to make things cheaper in the long run. The last TBI's were in 95 and stuff like the tempos were only used for a few years in the mid 80's so even the GM ones are going to become less common as the years go by.
The 90's only came in the early 454 trucks. In my area they rarely turn up. The 2.8 were 33, 4.3 were 45. 5.0 were 40. 5.7 55. Later 454's were 80. The HO 5.7's were 65. Multiport takes more fabrication but especially now days there are lots more options for bosh style injectors which ultimately tends to make things cheaper in the long run. The last TBI's were in 95 and stuff like the tempos were only used for a few years in the mid 80's so even the GM ones are going to become less common as the years go by.
Megasquirt II (PCB 3.57) IIRC bumped the CPU from 8 bit to 16 bit processing and has a faster clock speed.
It does much much better for low speed drivability with large injectors, IIRC the reference table for the injectors is 64 places instead of 16 thus it has better resolution and control.
Some of the guys on Turboford are running 65lb, 75lb, and 95 lb hr injectors with a Megasquirt II. Some who upgraded from Megasquirt I said low end driveability and idle is much improved.
Ergo, Megasquirt I is cheaper but Megasquirt II is worth the extra money for performance applications.
It does much much better for low speed drivability with large injectors, IIRC the reference table for the injectors is 64 places instead of 16 thus it has better resolution and control.
Some of the guys on Turboford are running 65lb, 75lb, and 95 lb hr injectors with a Megasquirt II. Some who upgraded from Megasquirt I said low end driveability and idle is much improved.
Ergo, Megasquirt I is cheaper but Megasquirt II is worth the extra money for performance applications.
A stock Tempo HP is rated at around 148hp, so I would presume the injector can handle that much, at least. Or did I get my figures wrong?
I have both Tempo and GM TBI units. I'm just being lazy since it'd be easier to install the tempo unit give its diminutive dimensions. The bore spacing on the GM is way wider than my Weber, or than the hole in my log which was cut to accomodate a Weber. But, It's not like it would be some great engineering feat to make a suitable adapter. One of these days I'll have to buy a drill press, though...
Anyhow, the GM unit is looking more and more promising since I can run two smaller injectors and get better resolution at the low end while still supplying ample fuel at the top end. Those 1-3/4" butterflies are awfully large, but I guess that matters less in an FI application.
Anyhow, the GM unit is looking more and more promising since I can run two smaller injectors and get better resolution at the low end while still supplying ample fuel at the top end. Those 1-3/4" butterflies are awfully large, but I guess that matters less in an FI application.
FYI tempo butterfly is about 43mm, or 1.7".
Thats about what I get. Around 3" mounting bolt spacing.
Thats also what the GM non 454 2bbls are. The small GM's were 35mm
IF you are going to go with a 2bbl that big I would recommend getting your timing controlled by the computer also. Throttle response can be an issue with throttles that big. I found that being able to tweak the timing to smooth things out is much easier than messing with a non linear throttle cable.
Thats also what the GM non 454 2bbls are. The small GM's were 35mm
IF you are going to go with a 2bbl that big I would recommend getting your timing controlled by the computer also. Throttle response can be an issue with throttles that big. I found that being able to tweak the timing to smooth things out is much easier than messing with a non linear throttle cable.
I think the MS 3.0 and 3.57 boards are functionally the same. Primary difference is the 3.57 is a factory assembled unit using mostly surface mount components (harder to diy repair for most people). The 3.0 uses more traditional through hole parts and is available as a kit or assembled by some vendors. Im not sure if you can get the 3.57 with a MS1. The 3.0 can go either way.
I'm with you TJ. Can I get the M to control a DUI Ignition, though? I think not since it uses the 4-pin module. since I already dumped an absurd amount of dough on he DUI, I don't really want to swap it out. Plus, it does perform admirably.
You mentioned that the smaller GM units have 35mm butterflies. I thought the choices where 1-3/4" (44mm) or 2" (50mm). Are you saying that they are actually 35mm and 44mm and that there are no 50 mm units? If so, I'd be quite confident that the 35mm would be fine as I have a 38/38 on there right now and it is very smooth.
You mentioned that the smaller GM units have 35mm butterflies. I thought the choices where 1-3/4" (44mm) or 2" (50mm). Are you saying that they are actually 35mm and 44mm and that there are no 50 mm units? If so, I'd be quite confident that the 35mm would be fine as I have a 38/38 on there right now and it is very smooth.
I have not seen the 2.5L 1 bbl listed anywhere. Its base is fairly large so I never really looked at it. Some of the lists I have seen say that the 2.8L used a 2bbl with 35mm bores and 33 lb hr injectors. I have no idea what they came in and have never seen one that I know of. I assume it must have been an s-10 option? This may be a good thing to look at for something like the 200. The smaller bores should require less modification to the log and better drivability. That one is not on all the lists so I wonder if it was a not sold in the USA?
The lists I have seen say that the 4.3, 5.0, 5.7's all use a 43mm bore, just injectors vary. The 454's were 51mm. The Holley projections and 'upgrades' for the GM's were 52mm. I would assume their target market was the smaller motors so it would have made sense to pretty much build the 454 one since it was not all that common compared to the small blocks.
The lists I have seen say that the 4.3, 5.0, 5.7's all use a 43mm bore, just injectors vary. The 454's were 51mm. The Holley projections and 'upgrades' for the GM's were 52mm. I would assume their target market was the smaller motors so it would have made sense to pretty much build the 454 one since it was not all that common compared to the small blocks.
As for the DUI you can either retrofit a 7 pin module or use the MS2 3.0 or 3.57 with the direct coil control option. Both ways you have to lock down the mechanical advance. I believe you can also use something like a MSD6 in the chain also if that kind of thing excites you.
I could look for the smaller unit, but I'm sure the 1-3/4" could work reasonably well with good programming and small injectors. Maybe making a somehwat tall adaptor would help, too. As for the DUI unit, I guess direct coil control would be a simple solution. I don't see why I would need a module if the MS is controlling the ignition anyhow.