2.5L ('98-'01) Turbo build - 2.5 sohc - need some help

[Ben Horrom]

Howdy, I'm a senior in high school with a 1999 ford ranger regular cab with the 2.5 lima w/5 sp. I want it to be turboed eventually, hopefully by next year after graduation. It's my only way of transportation as of now. I'm not rich, so I bought another 2.5 engine with a blown headgasket and chipped piston (to slowly build over the winter so I don't have to take my truck out of commission) for 50 bucks lol. Long story short I got it tore apart and find a crack in the head right at the valve seat. But - I am going to turbo this truck, I've tried doing research and i'm finding a lotttt of info on the 2.3 lima, and the 2.3t from the turbocoupe and SVO's and whatnot. It seems like there is more aftermarket for the 2.3 engine, but I want to use what i've got. I can just use the head from my stock engine when I start tearing it completely apart next year anyway, once i get a full time job and another daily.


I just want some help finding parts, I'm on a budget but trying/willing to save. I pretty much know the majority of parts I will need, the problem for me is finding the parts. I'm not super experienced, I just think building this engine will be a great experience and I enjoy it.

I know I will need:
1. forged pistons/rods with lower compression ratio
2. bigger injectors/fuel pump
3. turbo/intercooler, piping
4. turbo exhaust manifold
5. a tune

Question is, can I use 2.3 rods/pistons with the stock crank?
Do i need some special formula of rod/piston mix and matching to get the right compression ratio?
Where do i find bigger injectors... Are they like a universal fit? ---> how much bigger should i go? [same with fuel pump]
My stock crank is fine, right? Or would it be easier to just get a 2.3 crank and use all 2.3 internals?
The block is the same as a 2.3, correct?
Can I use 2.3 pistons/rods with the 2.5 crank or no... Can I use turbuocoupe internals with my engine?

I'll take all the help I can get, sorry for the jumbled huge confusing thread i just made, but thanks beforehand for any help you might have

 

[corerftech]

From what I gather, the 2.3 and 2.5 on some years have differing crank journals. Rods are 5.45 and 5.2 in length (If the info I got was correct).

The crank journal issue may come into play depending on the year block you have.

Someone else will have definitive info.

Great score on the core engine too.

 

[Ben Horrom]

I see... just to clarify, the crank journals are the part of the crankshaft that sits on the bearing race, right?

Ah, so it would basically be a nightmare to mix/match a 2.5 crank and rods with 2.3 pistons or some other combination

I'll take pictures of the part numbers of the rods/pistons, crank, block etc. later, and do some more comparing.

Would it be beneficial to swap the crank over to a late 2.3 crank (if the journals are the same size) so I can just use 2.3 internals?

also found this on this forum, i'm guessing the 'smaller crank journals' are being compared to the early 2.3 and not the 2.5...? - And thanks for the response

 

[Ben Horrom]

I've been doing some more reading: if i kept the boost at a modest-ish level, could i keep the stock rods and crank if I got some forged pistons? [with lower compression ratio]?

 

[corerftech]

Yes it’s the main journals that need to be matching and the 2.5 has a single diameter used for its years of production while the 2.3 used, for various years, two diameters. The block you have would need to match the donor crank diameter. I don’t know the years for any of it.

But as I understand (your later post), you can run a turbo on stock compression, just not so much boost. 9:1 based on my research is limited to about 5-6 psi on gasoline. Around 9:1 is the stock CR for the limas. I think I saw a post on the turbo coupe engines that mentioned 10psi or so but I expect CR is lower, maybe dished pistons…… again someone here has intimate knowledge of both.
Alternative fuels allow more. That’s a rabbit hole I think for a stock EFI engine.

 

[Ben Horrom]

Ok i see what you're saying. I'll have to try to find some more info on the different cranks/blocks etc.

Right, so the most common ways to lower the CR is dished pistons or shorter rods...? What would be a good CR for 10+ psi?

 

[Ranger850]

You're probably gonna want @RonD in on this conversation.

 

[RonD]

Not me for turbos
And "modest boost" is like having enough money......................it never happens

You only know you added too much boost when something breaks and not until then

Designed and built Full Race engines blow up..........................

So do your best and read what others have done, and what's one more PSI of boost, if 5psi was OK then lets try 6psi

 

[corerftech]

I believe that puts you in 8-8.5:1 area.

There are some charts that are generally accepted as the rule of thumb- they show static compression with “x” psi or bar of boost and the calculated dynamic/final CR.
That would dictate based on fuel quality what your static CR could be/would be limited to.

In my research I have seen many 8:1s in service, pump gas and modest boost. Massive boost with exotic fuel.

Good Vibrations Motorsports

www.goodvibesracing.com

There are many similar charts. FCR seems (on gasoline) to tap out at 13:1

My example which is generally accepted, 9:1 CR plus 5/6 psi puts the FCR at 12.x-13:1
Timing limited, people run the engines for reasonable times and make good power safely.

Timing will play greatly into the math.

Per chart:
Then 8:1 puts FCR at 13:1 with 10 psi. I’m sure fuel quality will make that vary greatly but the convention
Why 13:1?? Dunno. But folks “general accept” 5/6 psi on pump premium 93 octane as the top end at 9:1 which lands squarely at 13:1, then 8:1 modified engines with same fuel at double the boost, squarely at 13:1—— there is some voodoo logic behind that number and math system.

But don’t bank on my statements or that chart. I just read really well lots of white papers on the subject.
Anybody- can the 13:1 be explained?

 

[Ranger850]

Not me for turbos
And "modest boost" is like having enough money......................it never happens

You only know you added too much boost when something breaks and not until then

Designed and built Full Race engines blow up..........................

So do your best and read what others have done, and what's one more PSI of boost, if 5psi was OK then lets try 6psi

I didn't know if you knew the answers to the 2.5 with 2.3 internals, but I think OP figured that part out.

 

[scotts90ranger]

the crank journal thing was in like '88 so not a huge deal on this depending on what parts are used...

2.5L cranks have more stroke than a 2.3L crank but have the same bore so to use 2.3L rods and pistons you need a 2.3L crank, things are designed around piston pin centerline and crank stroke to get compression ratio and so forth...

I haven't looked into it much but I used to hear the hypereutectic pistons used on the 2.5L weren't the strongest...

 

[alwaysFlOoReD]

You can also play a bit with head gasket thickness for CR

 

[Ben Horrom]

I believe that puts you in 8-8.5:1 area.

There are some charts that are generally accepted as the rule of thumb- they show static compression with “x” psi or bar of boost and the calculated dynamic/final CR.
That would dictate based on fuel quality what your static CR could be/would be limited to.

In my research I have seen many 8:1s in service, pump gas and modest boost. Massive boost with exotic fuel.

Good Vibrations Motorsports

www.goodvibesracing.com

There are many similar charts. FCR seems (on gasoline) to tap out at 13:1

My example which is generally accepted, 9:1 CR plus 5/6 psi puts the FCR at 12.x-13:1
Timing limited, people run the engines for reasonable times and make good power safely.


Ah, thanks for that link. If I have to lower the compression ratio that much, what all goes into that? Will changing the piston to a dish shape lower it enough to make a difference?

 

[Ben Horrom]

@scotts90ranger, thanks for the input. If i can't find any forged turbo specific pistons (for the 2.5) for a reasonable price I'll have to think about swapping over to the 2.3 stuff.

I've heard about the head gasket stuff, kinda seems sketchy but if it works i'm down to try lol

Sorry to bombard you guys with questions, but how exactly do I measure the CR? And do small changes (aka: fractions of an inch) change the ratio very much? Especially if i swap the pistons, how do I recalculate the CR? thanks a lot guys, this information is really helpful

 

[RonD]

If you haven't been here: https://esslingeracing.com/

Then you need to, if its anything to do with 2.0l/2.3l/2.5l SOHC Limas they have done it