Roush S351 engine build specs?

2000xp8 · Dec 12, 2006

Had a friend ask me about what was done to s351 engines, specifically the block and rotating assembly. I don't really know the answer.
Was there a difference in years?
Rumor has it, they weren't all that reliable, is this true? If so, is it true of all of them?
Or was it the computer tuning?

I figure marcus and some of you other guys know the truth.

marcus95 · Dec 13, 2006

Joe,

Bore and stroke 4.00x3.50 inches. Crank was not forged or anything else. Compression was around 8.8:1 if I remember or something close. An old family company in Texas called AER built the rotating assembly. Here's the thing. I have seen lightning blocks and sporsman blocks so it appears they used whichever block they could get their hands on. Also, in 94-95 the pistons were hyperneumatic pistons that were notched on the top like the 83 mustang 6.0 pistons. The cam was a very little changed crane that Saleen called their custom grind.
My memory is faded on a lot of that so you are going to ask Scott to fill in the blanks as he has these motor apart on the floor of his garage at this very moment.

Oh yea, they changed the recipe slightly for 95 and up on the blower cars as they got upgraded a bit for boost bud didn't get forged until 96-97. They all even up until the end eltimately had fuel and tuning issues that made them so unreliable and go pop so often.

S351R"Animal" · Dec 13, 2006

94-98 they were almots all lightning shortblocks with flycut pistons. In late 96 they started using forged pistons. In 99 some of the cars received a sportsman block. It has beefier mains and has svo cast on the front of the block. The other blocks were just standard roller block. They can take some abude. They just don't do well under alot of bosst and with the stock tune there days are numbered. The mains will start to crack if the pistons don't go first. If your car makes alot of boost and you have to replace pistons make sure to have the block checked. 99 cars also received H-beam rods. 94-98 cars used a stock 351 rod. The forged pistons were made by wiseco.

marcus95 · Dec 13, 2006

THANKS Scott!

saleen065 · Dec 14, 2006

Don't you love it when a world of knowledge comes pooring out. Like opening an encyclopedia! Scott you are the man!

2000xp8 · Dec 14, 2006

Good info.
The fact that they used lightning shortblocks is a little concerning, since i i know that a vortech alone can do one of those in.

FASN8N · Dec 14, 2006

2000xp8 said:
Good info.
The fact that they used lightning shortblocks is a little concerning, since i i know that a vortech alone can do one of those in.

And many S351s were done in due to this. I think the lack of a decent fuel system and factory tune had something to do with blown motors too.

S351R"Animal" · Dec 14, 2006

The vortech isn't the issue. They will live at even 15 lbs of boost as long as the fuel system and the tune are up to par. If you own a pre 96 car then it is necessary to upgrade the fuel system an have the tune redone. Once this issue is solved the motors can be very reliable.

marcus95 · Dec 14, 2006

Right

S351R"Animal" · Apr 15, 2007

I have obtained a parts list that looks like an internal memo for the 351 used in the 99 cars. It has part numbers and the supplier.

joesgt281 · Jul 21, 2007

S351R"Animal" said:
I have obtained a parts list that looks like an internal memo for the 351 used in the 99 cars. It has part numbers and the supplier.

oh do share!

not to hijack this, but on the non-mechanical differences, what did Saleen do EEC-wise to integrate the 351 into an OHC car? Did they use the EEC that came in the particular year (like 99 for example), and somehow adapt the sensors to the 351 motor? Or did they take the OBD-II harness and EEC from like an Explorer, which still used the pushrod 302 a while into the OBD-II period, to make sensors easier to adapt?

marcus95 · Jul 21, 2007

They built a wiring harness to work with the multi pin processor for the 97 and up cars. Actually 96 and up cars. To get the most out of the setup thats what needs to be done to a 94-95 car including the fuel upgrades that Scott talked about.

Scott knows more about the motors. He probably has at least 3 or 4 on his shop floor right now.

If you want to know which guy took a hammer to the engine compartment to make the s-trim fit.....well then I can help you.

joesgt281 · Jul 21, 2007

marcus95 said:
They built a wiring harness to work with the multi pin processor for the 97 and up cars. Actually 96 and up cars. To get the most out of the setup thats what needs to be done to a 94-95 car including the fuel upgrades that Scott talked about.

Thanks Marcus!
so to clarify, they stuck with the eec that was in the 96 and up car?
i'm most curious about the ignition aspect. the 96 and ups used a crank trigger and no distributor, with coil packs.
and i'm thinking that the S351 cars all still had distributors.
did Saleen just figure a way to marry that into the non-distributor EECs?

marcus95 said:
If you want to know which guy took a hammer to the engine compartment to make the s-trim fit.....well then I can help you.

so i'm guessing that would be you??
awesome!

S351R"Animal" · Jul 22, 2007

Thet still have dist. but they use a crank trigger style ignition. When I get a chance I will go into it in more detail.

joesgt281 · Jul 22, 2007

S351R"Animal" said:
Thet still have dist. but they use a crank trigger style ignition. When I get a chance I will go into it in more detail.

That would be great.
I did some research from The Saleen Book which put a little lite on the subject:

Referring to the last year of the S351, 1999:
"It was still one of the fastest cars on the road, but its 351-CID pushrod engines was making the S-351 harder to bring in line with EPA and CARB regulations with each passing year. Saleen's engine management "strategy" - that complicated balance of computer codes that controls every aspect of combustion - for the big Windsor had been developed using the '96 Ford F-150 as a base. It was written around an exhaust system incorporating an H-pipe and a trio of oxygen sensors, a setup the state of California considered "deficient" as of the '97 model year. A CARB provision allowed this deficiency for two years, but Saleen had to gain special approval to continue 351 production in '99."

It was partly the complication of meeting an evaporative emissions system requirement that led to the S351s demise:
"Unlike the S-281 and GT, the S-351 had never been converted to a "returnless" fuel delivery system."

This suggests to me that for 96+ (OBD-II era) that they were possibly using the 351-based PCM, wiring, and sensors out of F150s. This might be confirmed if someone with an S351 could tell us if their cars have only 3 O2 sensors. I can confirm from my 97 GT and 98 V6 that these cars used four O2 sensors. And I suppose it makes sense that Saleen would not bother to try and integrate the original cars harness to the 351 since I believe they all started out as V6 models.

joesgt281 · Aug 3, 2007

Hey Animal,
Can you tell us if the S351 has only 3 O2 sensors?
Joe

s351rspeedster · Aug 3, 2007

joesgt281 said:
Hey Animal,
Can you tell us if the S351 has only 3 O2 sensors?
Joe

.....it should have 4 o2 sensors as Saleen Inc. used a stock h-pipe from Ford.

joesgt281 · Aug 3, 2007

S351RSpeedster...
The question is attempting to determine where Saleen sourced the wiring harness and PCM for the 96+ up cars. Specifically:

joesgt281 said:
This suggests to me that for 96+ (OBD-II era) that they were possibly using the 351-based PCM, wiring, and sensors out of F150s. This might be confirmed if someone with an S351 could tell us if their cars have only 3 O2 sensors. I can confirm from my 97 GT and 98 V6 that these cars used four O2 sensors. And I suppose it makes sense that Saleen would not bother to try and integrate the original cars harness to the 351 since I believe they all started out as V6 models.

If you wouldn't mind, would you check yours out and let us know?

S351R"Animal" · Aug 3, 2007

They modified the V6 harness and used a computer form a 96 Bronco that was reflashed. The alternator harness was from a 94-95 Mustang GT.

joesgt281 · Aug 3, 2007

S351R"Animal" said:
They modified the V6 harness and used a computer form a 96 Bronco that was reflashed. The alternator harness was from a 94-95 Mustang GT.

Well, would never have guessed that!
Thanks for bringing out this very unique bit of info.

Roush S351 engine build specs?

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