ANY info on 2.5L motors in 1991?

4570 Views 26 Replies 11 Participants Last post by PerformanceWithEconomy, Feb 26, 2011

PerformanceWithEconomy

Discussion Starter · Jan 30, 2011

Am looking for info on 2.5L motors that were supposedly installed in the Taurus in 1991. According to the info that i've been able to find, they supposedly switched from MPFI to SPFI in 1991 on the 2.5L motors. This would be a year earlier than all of the other Ford vehicles, as MPFI was not available until 1992 on most of their product line. Don't know how many 2.5L equipped Taurus' were sold in 1991, but Car-Part.com--Used Auto Parts Market does not even list that motor as being available for that year. ANY and ALL help appreciated. Sean
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1 - 20 of 27 Posts

84FordMan

· #2 · Jan 30, 2011

The only Ford 2.5L was the Duratec which was not introduced until the mid-to-late 90s in the Contour/Mondeo. However there was a Mazda K-series 2.5L that was found in the Probe. Does your engine look something like this?

http://www.danrsauto.net/search/images/1/thumbImg.php?s=740&i=224098-22.jpg&ms=0&mp=0&mw=0

Dubeckyj

· #3 · Jan 30, 2011

I believe he's talking about the 2.5L HSC I4, based off the 2.3 in the Topaz.

And yes, the latest year I can find is '90, which I believe would be MPFI. Are you trying to replace an engine? Would it be possible to swap the intakes onto an MPFI block?

Imaperson

· #4 · Jan 30, 2011

There is a wikipedia article on the 2.5 4 banger that was installed in the taurus from 86 to 91.

Ford HSC engine - Wikipedia, the free encyclopedia

perhaps that will help out some.

JW657

· #5 · Jan 30, 2011

I found a Taurus with a fully intact 2.5l a few months back. Sitting in a wrecking yard. If you're close to my location, I'll let ya know where to go looking for parts.

sheila

· #6 · Jan 30, 2011

Ahhh... My old 84 tempo 2.3 hsc (high swirl combustion). What a doggy piece of crap! It had the feedback carb and i couldnt keep a tfi (thick film ignition) module in it! Was life threatening getting on the hiway or trying to pass somebody.

JW657

· #7 · Jan 30, 2011

sheila said:
Ahhh... My old 84 tempo 2.3 hsc (high swirl combustion). What a doggy piece of crap! It had the feedback carb and i couldnt keep a tfi (thick film ignition) module in it! Was life threatening getting on the hiway or trying to pass somebody.

I think mine was an 86, it was carbureted. It was a dog :lol2:

Come to think of it, every tempo I've had was a dog.

sheila

· #8 · Jan 30, 2011

^+1!

Jeff K

· #9 · Jan 31, 2011

^^^^ +2

Wife has a CFI 87 Tempo. Fairly reliable except for eating 1 TFI and 1 fuel pump every 2 or 3 years. It was such a dog I was afraid to drive it for fear I wouldnt be able to get across an intersection without getting broadsided. Wife didnt seem to mind it though.

I go sick of dropping the tank to replace pumps I cut a hole in the floor under the pass seat to access the pump. After I did that, pump changes took me all of 15 minutes.

Steveg1988

· #10 · Jan 31, 2011

The 2.5L did switch in 1991 (according to the technical info page on the site) So did the 3.0 vulcan in 1991 to SEFI from MPFI. the 3.8L Essex switched in 1990. if y0u do track one down, see if you can also track down the 5 speed transmission so you can actually move out of your own way

PerformanceWithEconomy

Discussion Starter · #11 · Feb 7, 2011

Thanks to those with pertinent responses

To be honest, i'm building a 2.5L HSC motor from scratch to go into a 1994 Tempo. Yes, the Tempo's ARE slow, but like any other cheap, mass produced vehicle / motor, they respond pretty well to basic modifications that correct existing design deficiencies.

I'm taking that a step further and building a bigger, more powerful motor with custom intake, valvetrain, exhaust, heavily modified head, etc... Dyno simulation projections range from an estimated HP of between 175 - 200 HP. The reason for the variation has to do with specifics pertaining to the cylinder head and flow characteristics. I haven't gotten the head(s) onto a flowbench, so i'm having to "guesstimate" figures.

The ONLY places that i can find info pertaining to the change from SPFI to MPFI injection in 1991 on the 2.5 is in Ford literature and on this site. My guess is that the info on this site was taken from that same Ford literature. I can not find ANY info ANYWHERE ELSE to substantiate this info, let alone a 1991 Taurus with a 2.5L in the engine bay. I know that most folks bought these with V6's, but there should be at least a few of these around, let alone more info.

Any & all help appreciated from one Ford enthusiast to another!!! Sean
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loudsho92

· #12 · Feb 7, 2011

Claiming to double the horsepower at best seems like quite a bit. The vulcan might be a better place to start considering you will be at 140-150hp. It would be awesome to drop a SHO motor in...

Dubeckyj

· #13 · Feb 7, 2011

+1 I'm over $4k getting a vulcan to 200hp. To squeeze that out of an HSC, you'll be looking at a lot more. It would be a ton cheaper and a lot more fun to drop a V6 SHO motor in.

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JW657

· #14 · Feb 7, 2011

The HSC is a very reliable engine, but it is a dog.

Ford Six Performance Home/Index

The engine was loosely based off the inline 6 from my understanding. I would check over there and see what they do for performance, might give you some ideas. You'll be on your own, there's no after-market for your engine.

TempoTopaz.com :: Tempo Topaz Car Club of North America

I'm sure you've heard of them.

PerformanceWithEconomy

Discussion Starter · #15 · Feb 9, 2011 (Edited)

I'm one of the moderators of TempoTopaz.com and will soon be taking over the Webmaster position. As such, i'm well familiar with that site. Glad that some of you guys over here know of it though

As far as horsepower goes, do the math. The 2.5L HSC motor is 153 cubic inches. A reasonably well thought out normally aspirated street motor can achieve 1.5 hp per cubic inch without a lot of fuss. This would equate to appr 230 hp based on 153 cubic inches. Since i'll be running a heavily modified & decked HSO ( High Specific Output ) head, flat top pistons, appr 10.5:1 compression, a custom ground cam ( .550 lift with a split pattern 224 / 230 duration @ .050 ), full roller rocker arms, a TRUE high pressure ram air system, aftermarket C&L MAF, larger Throttle Body, Ford Racing injectors, high volume fuel system with a variable pressure regulator, a custom designed header, no cat, a high flow straight through muffler, etc... my calculated output of 175 - 200 HP is actually pretty conservative.

As far as running a Vulcan goes, that would be a LOT more work. My car is already set up for the 2.3 HSC motor. As such, the longer stroke 2.5 motor is a drop-in.

Other than that, making 200+ hp out of a Vulcan would be cake. It could pretty much be done using factory Ford parts IF you know what to do. If you've spent $4K and you're just hitting 200 hp, not enough homework or shopping around was done. I've got less than $1K into my motor & that started with a brand new FoMoCo block in the crate with all of the aforementioned custom made parts. Then again, i've got two less cylinders that i need to buy parts for, only one head and a single exhaust system, so that could equate for slightly higher costs. Not $3K worth though.... Sean
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Dubeckyj

· #16 · Feb 9, 2011

PerformanceWithEconomy said:
I'm one of the moderators of TempoTopaz.com and will soon be taking over the Webmaster position. As such, i'm well familiar with that site. Glad that some of you guys over here now of it though

As far as horsepower goes, do the math. The 2.5L HSC motor is 153 cubic inches. A reasonably well thought out normally aspirated street motor can achieve 1.5 hp per cubic inch without a lot of fuss. This would equate to appr 230 hp based on 153 cubic inches. Since i'll be running a heavily modified & decked HSO ( High Specific Output ) head, flat top pistons, appr 10.5:1 compression, a custom ground cam ( .550 lift with a split pattern 224 / 230 duration @ .050 ), full roller rocker arms, a TRUE high pressure ram air system, aftermarket C&L MAF, larger Throttle Body, Ford Racing injectors, high volume fuel system with a variable pressure regulator, a custom designed header, no cat, a high flow straight through muffler, etc... my calculated output of 175 - 200 HP is actually pretty conservative.

As far as running a Vulcan goes, that would be a LOT more work. My car is already set up for the 2.3 HSC motor. As such, the longer stroke 2.5 motor is a drop-in.

Other than that, making 200+ hp out of a Vulcan would be cake. It could pretty much be done using factory Ford parts IF you know what to do. If you've spent $4K and you're just hitting 200 hp, not enough homework or shopping around was done. I've got less than $1K into my motor & that started with a brand new FoMoCo block in the crate with all of the aforementioned custom made parts. Then again, i've got two less cylinders that i need to buy parts for, only one head and a single exhaust system, so that could equate for slightly higher costs. Not $3K worth though.... Sean
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$400 for roller rockers, $320 for custom valves, $165 for UDP, I got a steal for $150 for both heads decked and 3-angle valve grinds. ~$250 to get the spring upgrade issues sorted out. $220 for my CAI. $125 for my '01 UIM and 'tec TB. SCT was $450 with tax here in Canada. $500 for dyno tune with another $100 for smoke test & wideband 02 bung installation. Spark plugs, break-in oil, gasket sets and new head bolts. $3k, then. It all adds up. I'd love to see you hit 200 on an HSC for under a grand.

loudsho92

· #17 · Feb 9, 2011

PerformanceWithEconomy said:
a TRUE high pressure ram air system,

It is not possible to go fast enough for a ram air to make it remotely. I believe some one had done a test on a SHO and hitting 120mph was not even able to make 1psi. Cold air intake maybe but no ram air.

Do you plan to dyno the engine? It would be interesting to see the numbers.

PerformanceWithEconomy

Discussion Starter · #18 · Feb 9, 2011

Never said that i would stay under a grand, just that i had acquired the mass majority of parts mentioned above for less than $1K.

Through a LOT of research, careful shopping on the net and a LOT of patience, i was able to locate KILLER deals. On top of that, i'm more concerned with performance & reliability at a fair price than prestige of specific brand names at a high price.

As a few cases in point, i found a brand new 2.5L block in the FoMoCo crate for $175. A new crank set me back $50. Flat topped pistons, pins & moly rings were $50. Rods with SPS racing bolts were $9 apiece. A fully rebuilt 2.3 HSO head cost me NOTHING and a fully rebuilt 2.5 HSC head cost me $50. I'll end up porting & extrude honing both of them and see which one flows better. Aluminum pedestal mount 1.73 ratio roller rockers with a lifetime warranty were $120. Custom cam ground to my spec's was $60. I came up with the design after experimenting with my dyno simulator. NEW Ford racing injectors set me back $50. C&L MAF was $40. Larger throttle body was $28. Grade 8 head bolts were $7. Comp Cam's High Energy hydraulic lifters were $14. You get the idea.

Don't know how many other common parts from other motors can be swapped onto a Vulcan. Given the VERY limited use of the 2.3 / 2.5 HSC within the Tempo & Taurus, i would have to assume that the far more widely used and differently sized Vulcan would be more versatile in that regards.

Several of the prices that you quoted, such as rocker arms, seem VERY high to me. Especially since you've only got a 6 cylinder, not an 8. For instance, careful shopping with a bit of creative research on your part could have netted you pedestal mount 1.73 ratio full roller aluminum rockers for less than $225 total. This price would have also included 4 extra's rockers that you could have sold or kept as spares.

As to the ram air system, there are MANY different ideas as to what this constitutes. My idea of "ram air" is when you have measurable positive pressure in the air intake tract at reasonable cruising speeds. Just because one person's installation wasn't what they expected doesn't mean that it isn't possible.

With the proper tools and enough research, it's not that hard to design a system that actually achieves the aforementioned goal of producing VERY MEASURABLE levels of positive pressure within the air intake system. I would suggest picking up an inexpensive Magnehelic gauge and doing your own research on the matter. Combining positive air pressure with a well tuned intake & exhaust system and properly timed valvetrain, volumetric efficiency can be drastically increased. Sean
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PerformanceWithEconomy

Discussion Starter · #19 · Feb 11, 2011

Something else to think about. MOST intake systems are operating under negative pressure. That is, the air intake system is drawing air in from a spot that is under negative pressure. Minimizing this problem increases air into the system, even though it might STILL be operating under negative pressure. Kind of like having twenty holes in your boat and plugging 18 of them. You're still operating with losses that require more work & attention, but not nearly as bad as it was. Relocating the air intake to a point where you actually have positive pressure, no matter how small, can typically result in VERY positive gains in terms of throttle response and bottom end torque. Sean
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loudsho92

· #20 · Feb 11, 2011

PerformanceWithEconomy said:
Something else to think about. MOST intake systems are operating under negative pressure. That is, the air intake system is drawing air in from a spot that is under negative pressure. Minimizing this problem increases air into the system, even though it might STILL be operating under negative pressure. Kind of like having twenty holes in your boat and plugging 18 of them. You're still operating with losses that require more work & attention, but not nearly as bad as it was. Relocating the air intake to a point where you actually have positive pressure, no matter how small, can typically result in VERY positive gains in terms of throttle response and bottom end torque. Sean
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I will give you that it can help if the intake system sucks for a stock car. I forget where it is on a Tempo as I haven't had mine for a while.

The "ram air" system cam from airplanes when they could actually ram air in to the intake. For cars it is more of a gimmick as the car can not go fast enough to "ram" the air in. Granted you can move to a better place to draw cold air in or get a direct path but not to ram air in.

Now if you want to do some testing I am all for it.

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