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PostPosted: March 29, 2016, 12:36 pm 
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https://www.youtube.com/watch?v=2sQJPZYSoUI

Pretty much confirms what we've said here I think, that TBI injection doesn't do very much in terms of overall HP, although the TBI setup might be easier to tune?

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PostPosted: March 30, 2016, 9:26 am 
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Max HP is only part of the puzzle, I bet the EFI motor drives much better. It will learn throughout the rev range and throttle position range. It will work over a wider temp range, starts will be perfect hot or cold. It will start after a long winter in hibernation.

Graham


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PostPosted: March 30, 2016, 10:36 am 
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That petty much it, a carb can only match EFI in one area and thats WOT. Everywhere else programmable EFI is better.

Bob

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PostPosted: March 30, 2016, 10:05 pm 
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I'll take TBI over a carb any day. Also, on that engine there is still a computer running the timing with the carb.... that makes a huge difference over mechanical advance (which most carb guys run).

Here is a good video on EFI, done by an expert:
https://www.youtube.com/watch?v=6bkDKqoGSdU

Cheers.

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PostPosted: September 1, 2016, 3:06 pm 
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I did my first Throttle body EFI back in '89, on a '79 GMC 3/4 Ton pickup, with a 350. Installed an '82 Corvette Crossfire unit, upgraded the cam and a fresh set of heads. It worked right out of the box. Mind you, it was not common place back then. It ran great, much smoother than a carb, and had an awesome midrange. When that ECU crapped out, I swapped out the Crossfire unit for a Holley Pro-Jection unit. Almost identical to the Crossfire (I believe Holley made the throttle bodies for the Crossfire). Again, easy swap, easy to tune, and still better than a carb. Cost about $900 back then. I would recommend a throttle body unit over any carb if you don't have the ability or capital to go with port injection.

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PostPosted: September 3, 2016, 8:12 am 
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Have a friend that is installing a Ford 4.0 V6 into an Alpine. He has sourced a 4 bbl manifold and wants to install the Holley TBI instead of the port injection (he 77 y.o. and is afraid of the MegaSquirt learning curve). I told him I was afraid the heat of that sized engine stuffed into the cramped Alpine engine compartment would probably fry the computer. Am I off base?

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PostPosted: September 3, 2016, 8:24 am 
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Heat is electronics' worst enemy. If he can place it in the passenger compartment, up under the dash, it would be a better place for it. FYI, I placed mine in the scuttle of my Locost and not had any problems with it at all.

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PostPosted: September 3, 2016, 10:10 am 
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We're a funny bunch. There was another thread much like this one about a bolt-on TBI unit, with the poster saying he'd take a carb over that any day. I posted pretty much all the reasons why EFI was better and got lectured on how carbs were in fact better. Wonder where those guys are. I think it was a Holly product.

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PostPosted: September 3, 2016, 1:09 pm 
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I can go either way on this stuff, and the answer is different for different people. We use our cars differently and we have different backgrounds.

For my formula car a carb works well, not much is asked of it really. The alternative with a heavier battery, an alternator an all the extra wiring makes little sense. I even enjoy the moment I spend during the first start of the day using the palm of my hand to choke while I reach into the cockpit and hit the start button.

If you don't already have an education in carbs, it doesn't make so much sense for most people to learn all that. That goes at least double for a street car which is much more demanding of it's carb.

Injection can be quite a hill to climb though if you have to learn how to use a computer to even get started.

In the Holley TBI the computer sits inside where the float bowl would go, so it can get rather warm. Good embedded computer chips are specified for high temperature though. The one I am working with is rated from -40F to +302F ( which to me seems to make it perfect for a small block Ford :rofl: ). This is the temperature of the chip, not the air temp - but you can see it is a rather robust unit compared to what is in your laptop or cell phone...

I have no idea what the parts are used in a Megasquirt though and you might find a rather different answer...

I think the Holley TBI might be a good choice for someone with a pretty standard engine who doesn't look forward to learning a lot about computers or carbs for that matter... Fancy or radical cams, porting or unusual intakes and exhausts might be more difficult for it...

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PostPosted: September 4, 2016, 8:04 am 
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Don't know about the components used in the Megasquirt, but the directions tell the user to install outside of the engine compartment. The last I heard (years ago) that was standard automotive practice.

I suppose it boils down (no pun intended) to the cooling capacity of hot air. How much 220 degree air flowing through the TBI unit is needed to keep the chip temperature rise below 80 degrees? At idle in heavy traffic, I think there is a good chance the 'puter would be on the loosing side of that equation. A real problem is that in order to cool the engine in an Alpine, the engine compartment is sealed off to encourage as much air movement as possible the radiator.

Bill


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PostPosted: September 4, 2016, 1:39 pm 
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BBlue wrote:
Don't know about the components used in the Megasquirt, but the directions tell the user to install outside of the engine compartment. The last I heard (years ago) that was standard automotive practice.

I suppose it boils down (no pun intended) to the cooling capacity of hot air. How much 220 degree air flowing through the TBI unit is needed to keep the chip temperature rise below 80 degrees? At idle in heavy traffic, I think there is a good chance the 'puter would be on the loosing side of that equation. A real problem is that in order to cool the engine in an Alpine, the engine compartment is sealed off to encourage as much air movement as possible the radiator.

Bill



It's remarkably random as to where they put ECUs on modern cars. I'd guess it comes down to packaging more than anything now. They are located anywhere from inside the air intake (for cooling) to inside the engine valley (rigidly mounted to a vibrating engine, right in front of a hot turbocharger). There really are not a lot of ECU failures anymore so the hardware must be pretty durable.

Still, there is no question keeping things cool and unshaken is better.

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PostPosted: September 4, 2016, 2:18 pm 
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ECM`s have been fitted into diesel injection pumps for years. Immersed in very hot fuel and subject to vibration and pressure, thats a testament to the durability of modern electronics.

Bob

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PostPosted: September 4, 2016, 8:15 pm 
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It is not simply "modern electronics". I can say from experience that under-hood components are specially designed for this rugged environment. That and they go thru a rigorous testing plan to prove them out.

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