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P/P HEAD, REWORKED I/E MANIFOLDS

2343 Views 5 Replies 3 Participants Last post by  valiant67, 
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Hello,

I am in the process of looking for a couple extra mpg from the ole 2.5 liter TBI. Since it is a daily driver, I want to keep things simple and balanced. My goal it to develop torque, to fasciitate increased fuel economy; ultimately, I am hoping to hit 41+ without a turbo.

The engine is stock and original, it just went over 100,000. I have procured 2 donor heads; an 87 T1 and a 94 TBI. Both heads were cracked and both are Mexican 782's; the T1 head was unfortunately cracked beyond normal repair but the 94 TBI, despite some damage is usable.

I have chosen to use the stock intake and exhaust manifolds from the 94 TBI for the project. I have chosen Mr. David Endrigo of Flowtecnics, Poulsbo Wa, to perform the port/polish and flow-bench work along with the rework of the stock manifolds. He has completed the rework on the exhaust manifold and is currently reworking the intake manifold. He was impressed with the exhaust design but very disappointed with the intake manifold's. He told me that it needs the T/B higher and a less severe turn at the base. He has a couple of ideas, he isn't sure if he wants to build an insert, custom riser or build up the base of the intake for that T/B. Either way, some improved fuel delivery is" in the works".

For the head, all the work is for torque, multiple angle valve job, we didn't discuss cutbacks for the valve stems but he will do it if he feels it adds to the balance. The brain, or cam is also from the 94 TBI; it is getting a custom regrind in accordance with Mr Endrigo's specifications.

I am very excited and have, high expectations. The auto currently maintains a steady 26/31 fuel economy, which I am actually pleased with, just not satisfied. I use an aftermarket coil, 8.2 wires, E3 plugs, a K&N, Mobile 1 and a Dynomax cat-back for the tune, currently @ 12 BTDC. Over the past month, I have installed a new Gates timing belt/tensioner, an ASP crankshaft under-drive pulley with replacement power steering/alternator belts. She feels pretty good these days

I am using the T1'S exhaust springs and valves for the head, I don't think there was anything else from the T1 that is improved over the TBI for Turbo use? Is there, were the valve guides the same?

This coming spring, if the Sundance makes it through the winter, I plan to add the T1 system to this 2.5. I will keep everyone informed of the progress.
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Bob Lincoln

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It's ambitious, and I hope you see some improvement. But honestly, no matter what you do, the only way you're going to get 40+ mpg from that car is to drive at 40mph on flat roads the entire time, with no stops or traffic.

I would NOT use a head with any cracks at all, you are bound to have a failure, especially as soon as you remove more material. There are some good articles on modifying this head (see the work that Mike Holler has done on it). It's all too easy to grind too thin in some spots and cause a crack. The reason these heads don't breathe well is that they are bulletproof, and drilling out too much or in the wrong areas can sacrifice life.

A K&N drop in filter is a total waste, as is one that is mounted out in the open underhood. So are the fancy wires and coil.

Your best investment would be to convert to a 5-speed for at least a 3-4 mpg gain guaranteed.
 
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BobLincoln:

-I like the idea of changing over to a 5 speed! I am saving that for last but as you suggested, perhaps should have been done 1st! The only time I ever used an Automatic transmission and didn't fully loath it it was while commuting 3 1/4 hours a day in Japan.
-thanks for the honesty Bob. Unfortunantly, I do plan perform a couple of changes which will no dought be counter productive to fuel economy: the use of 15 or 16" wheels and rear disc brakes (including the hubs to make use of Caravan wheels with the larger bolt pattern). Two other changes that added weight were the body parts from a 94 Duster and a stereo for my daughter. Both were cosmetic, if you will. She likes the look much more and completely enjoys listening to some music from time to time.
 
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Hello,
Finally installed the port and polished 94 intake and exhaust manifolds and T/B riser last weekend. The car is running exceptionally smooth. One of the most noticeable differences is how smooth it shifts now. It still isn't a race car but it sure is making more torque. Ultimately, what I expected was to feel more torque. Whereas I have not "measured" it, the seat of the pants certainly feels a pronounced difference.

The head is ready, I hope to have it in this weekend. I also have the stock exhaust from a 91 Turbo Shadow; I plan to use it to the muffler. I have a couple choices for mufflers but the one I think is going to provide the most SPANK is the Borla 2.5" XR1, used with the dual 2.5" tips. I have tried this on a variety of systems, the last being a 98 Plymouth Neon Expresso. It realy woke up the 2.0 liter DOHC! It was a bit much for the Neon and may also be for the Sundance. I actually hope it fits in well but I believe it will need a turbo to be in balance with the rest of the power plant.

I will let everyone know the specks on the P/P and how it performs as soon as I get it in. I am very excited, once again, it still isn't a race car but, whatever this 2.5 TBI is capable of, I will have a pretty good idea very soon. I expect that it will develop even more.
 
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