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Old 08-11-2000, 09:26 AM   #1
Scottie
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Post How 'bout HPV 3B vs TEC II?

The reason I'm asking is instead of doing a full blown PEM system, how about just the HPV 3B?

In a NA application where the intake is kept stock, is there really a need for the fuel management portion of the equation? Since the intake is stock, there shouldn't be any MAF errors on MY99s or VE changes with MY00s that need to be corrected for, and I would think the stock fuel delivery system would be up to the task (no need for larger injectors or fuel pump). Therefore, I would guess the end result of Shiv's tuning of the TEC-II on an otherwise all stock car would wind up being relatively close to the actual stock fuel mapping.

I've read the many many old posts about hesitation problems, flat spot @4000 rpm, ECU resets, over-sensitive knock sensor, stock ignition timing that can't take advantage of higher octane fuel, etc., etc.. A lot of this could very well be associated with ignition issues and the ECU retarding the timing. Using something like the HPV 3B would certainly seem to look like a possible solution to some of this stuff.

I'm trying to say the same claimed performance gains can be made with just the HPV 3B vs the TEC II. However, on an otherwise stock car, I'm guessing the end results would be pretty close. I'm not even trying to say that the HPV 3B would result in gains, just hopefully that it would prevent the power losses associated with the some of the above mentioned problems.
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Old 08-11-2000, 11:46 AM   #2
iceinject
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i'd be willing to bet that not one single person who is going to get the tec-II will
leave their car stock. any takers?
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Old 08-11-2000, 01:15 PM   #3
CNC84
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If you are keeping the engine stock then what is the point of getting any new form of engine management at all. For the price of either of these systems you could upgrade the suspension, tires, or pretty much anything else you wanted to upgrade I would much rather have an awesome suspension than another 5 hp. But that's just me.
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Old 08-12-2000, 12:01 AM   #4
Scottie
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That was kind of my point. If you're going to keep your engine stock, then there's not much justification for the cost of the "PEM" system. I'm guessing the HPV 3B, which is basically a TEC II minus the fuel management stuff, would cost less.
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Old 08-12-2000, 12:04 AM   #5
shiv
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I'm not so sure that all of the gains are from only ignition advance changes. Fuel plays a big role in thing as well. MY00 cars seem to run very rich under boost. Leaning it out is sure to extract a few ponies. While Electromotive's HPV is a good system, a TEC-II system is only ~$600 more. That's not a bad price to pay for complete fuel control. I think the HPV is best left to those who need to retain the stock fuel system for some reason or another.

Shiv

[This message has been edited by shiv (edited August 11, 2000).]
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Old 08-14-2000, 05:39 AM   #6
Scottie
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Chris,

I've already taken care of the suspension part. Besides my post is not meant to be about where ones money is best spent. From what I've seen in old posts, that subject has been done many times before. No, my post is meant to be about the HPV 3B vs the TEC II.

There is a recent post by jhuang where he gives a review of the TEC II on his otherwise stock car. He reports significant improvements in the midrange and feels the car performs better all around. Based on this, I was just wondering how much of the improvements he felt were the result of better fuel management and how much was the result of better timing control.

I guess without out the stock fuel and timing maps it would be hard to know for sure how much they differ from those programmed into the TEC II for an otherwise stock car.
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Old 08-14-2000, 01:11 PM   #7
shiv
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It's more than just two squirts. It's when the two squirts occur. I don't know of any stock engine management system that runs phase seq. fuel injection. They almost always run full sequential instead. This is because phase sequential operation creates more pollutants during cold start (before the intake valves heat up), which is critical to EPA testing. Just another situation where performance takes a back seat to emmission (even if it is just for a few seconds during cold start).

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Old 08-14-2000, 01:38 PM   #8
CNC84
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I guess if you really get down to it the JC sports torque chip could do what you are looking for in a much more crude way. The point of thier chip is also to improve the midrange torque, it probably wouldn't be quite as effective as the Tec or the HPV but it would probably get you close for a lot less money.
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Old 08-15-2000, 12:01 AM   #9
shiv
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A good portion of the throttle response and low/midrange torque gains is a result of the TEC-II's phase sequential injector firing order. One out of two fuel squirts is fired at the back of the intake valve. Since the valve is hot, the fuel atomizes immediately. Next injector firing squirt happens during the intake stroke, when the inrushing air pushes both the new squirt and the previous pre-atomized fuel vapor into the combustion chamber. The entire fuel/air mixture swirls and mixes together. Then the piston starts to come upwards, compressing the intake charge. When the spark is fired, it is fired for a unusually long 120 deg of duration. At lower engine speeds, when air/fuel swirling/mixing is not complete, the long spark helps facilitate the entire burn. All these events improve low-end to midrange power and throttle response. In other words, I don't think fuel or ignition alone can take the credit.

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Old 08-15-2000, 12:30 AM   #10
Scottie
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Shiv,
Do you know for a fact that the stock ECU doesn't do the same thing? I thought that a lot of modern engine management systems do that two squirt thing? Also, do you know what the max. duration of spark is for the stock DIS system?

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