• To ALL forum users - As of late I have been getting quite a few private messages with questions about build ups here on the forum, or tech questions about your personal project. While I appreciate the interest, sending me a private message about these topics distracts from, and undermines the purpose of having a forum here. During the day I wear many hats as a small business owner-operator and I work tirelessly to provide the absolute best service possible to you, our valued customer. When I created this forum I rounded up some of the best minds I knew so that any tech question you might have could be asked and answered by either myself or one of my highly experienced moderators, this way the next time this same question is asked the answer can be easily found and utilized by the next IH enthusiast having the same question. This allows me the freedom to run the day to day operations of the business and minimize the impact to shipments and shop activities that these distractions can cause. It is of the up most importance for me to complete the daily tasks in order to best take care of you our customer, all the while providing you a forum to get the level advice and input you have come to expect and deserve from the premier IH shop in the country.

    So with that I ask that anyone with a question about one of our build ups or a general tech question to please use the forum as it was intended. I am absolutely available by telephone to answer your questions as well but at times may direct you back to our website to better field your question or questions. Most other private messages I will be glad to answer for you.

    Thank you for your understanding.

    Jeff Ismail

Specs on OEM 152 Turbo Setup?


New member
I want to turbo my project Scout. Please don't bother with the "just swap engines" discussion. I have access to pretty much any turbo I want for free or cheap and just want to play around with it.

I was wondering if anyone sells the oem uppipe/downpipe/manifolds still, what the oem turbo specs were(max boost, inlet and outlet diameter, etc), oem carb configuration for the turbo setup, and if anyone has any experience on this what the max boost the 152 can handle readily(I'm thinking I want to run the 4-5psi range, cause I'd imagine 8 or so is tops for this, but looking for any advise on this).

Robert Kenney

Super Moderator
I won't try to dissuade you from a turbo 152 project.

A couple of notes on boost pressure limits..
99% of the time the limit will be based on how well you know how to tune an engine and manage thermal loads imposed by said turbocharging. I would not hesitate to run 10-15 lbs on a 152. They have massive bearing load areas, very strong pistons and an gorilla of a forged crank.

The stock 152t was a draw threw configuration and a dinosaur turbo. It made about 4 lb. Draw through adds air charge cooling from the fuel flowing through the compressor.
Todays will perform way better with less stress imposed on the engine.

Beware of:
time at high load.
Proper ignition timing above ambient pressures. Stock wot at rpm is 34-36 degrees. Boost retard 2 deg/pound above that.
Manage fuel like there's no tomorrow. Resist trying to lean in order to make power. Keep it richer than 11-1 at all power levels above ambient manifold pressures +2 lb.

Many 152's are of a non quench design. I recommend swapping in flat top pistons and a cylinder head off of a e304 with the "d" combustion chamber. Run .040 quench distances. Run 8-1 or lower for above 6 lb.

Don't get caught up in a big turbo. Rather size the turbo for peak hp like 160-170 max. You'll build boost earlier and make more torque.

The rest is obvious for a intermediate engine guy.
Last edited:
as I get closer to bolting on the turbo, I recognize a vital need to assess the fuel mixture issue. I am looking at installing an innovate wide-band sensor kit to monitor a/f mixture under operating conditions. I see where I can take the analogue output and input it into the real-time data log feature in my megajolt jr.
This way I can plot rpm, manifold pressure, advance, and a/f at any particular point. So you suggest a target 11:1 a/f when under boost? If I install this device with the stock 1940 carb and track how it performs, I can get a feel for what makes it run well (not the same as optimal) as a stocker, as a baseline for when I use the side draft carter.

I have found that the quench I have (it's as you state) seems to favor less advance.

Hoping for another binder nut to enter the turbo zone….


New member
Thanks for the responses Robert and Mark. Glad to see the real support, the few posts I could find (most dating back to early 2000's) on multiple forums just resulted in "why would you do that, just put in a v8" responses.

I'm pretty set on doing this, whether it's anything like the factory 152t or not ;) my brother-in-law owns a diesel performance company and he gave some word to his sponsors (he has a 1000+hp cummins running some wild turbo setup) and has two itching to support my project in exchange for some local presence in events around here, and I normally tag along with him anyway. So the turbo isn't really a hard part in this for me. Picking it is a little more challenging ;)

if 10-15 is safe, I'll definitely squeak a little higher than 4-5, I'll have to chat with the two turbo manufacturers that are interested in my project about what I can get to spool at the lowest rpm possible for a project like mine and possibly run to the 10psi range. I don't need rock crawling spooling potential but the oem from what I read didn't really start to spool until 2000-2500rpm.

I find it interesting about the short chat on leaning for power, when the common issue I saw trying to find any info on something like this was people running Rich in mid rpm before spool up soaking down the cylinders in fuel. Is the factory carb acceptable for this application? I read somewhere than the oem 152t had different jetting but everything else was the same, does anyone know what the jetting change was so I have a baseline?

Considering the timing concern (understandably) is there a recommended ignition changeout in your opinion from the oem distributor be it electronic distributor or other ignition system?

If flat top pistons are the way to go I'll probably just go with ihparts full motor kit with the cam grind. What do you think my realistic risk is to run it on the motor as is?

The project is budget conscious but I'm not afraid to put down a few bucks to do it right. The body is starting to come off this weekend for a frame and axle sandblast and pro 15 job, then the ihparts lift kit with a 1" body lift to help clear the exhaust and manifold setup. Then I'll be kicking on a disc brake conversion and then the motor build begins. I gotta get my motor stand home from it's previous location and start cleaning up and doing a real condition check. It ran the Scout out of the junkyard but other than that I'm not sure on it yet.
Last edited:

Robert Kenney

Super Moderator
I have a spec chosen gt garrett unit for my 4 popper Scout project. A bigger unit than you need but because my intensions are 190 inch displacement and highly modified induction and fuel delivery system my yield will be in the 250 hp range and 5500 rpm, I chose a turbo with a map and efficiency band that puts me in the sweet spot so to speak. I will have head room to make the same power at altitudes like 8000 foot density altitude.

Read this thread about my intentions.

For any carburetor application utilizing draw through you need to boost reference the power valve. The stocker is not a good choice. I would use a 2300 Holley 2 bbl with the proper power valve mods. Lots of info out there on the mods.

I would not mess with cheap parts. Only ones made worth a hill o beans in an application like this are silvo-lites. The form is provided by International parts america IH Parts America store - International Scout parts
They vehemently support the IH community. So that being said, if you chose to buy parts elsewhere ( I hope you don't) don't post name and such here as it takes food from their table. We appreciate keeping IH's on the road but also keeping this form available for every one to use. Hope you understand my point and keep your build thread going.
For a definitive description of the original 152t setup, see my article, with lots of pictures, on the bb under knowledge base, history. You'll find the data you seek wrt jetting and timing. The original setup was a stop-gap measure until the 196 was made optional. The draw-through setup wasn't optimal but probably was most welcome at higher altitudes where the turbo would restore lost performance, and that 152 couldn't afford to lose what little it had. I understand that it was capable of 7 lbs. Boost, but the local parts dealer (in mesa, az) told me he hated the things because people kept blowing them up due to abuse. Be that as it May, or not!, the crown jewel of the setup was the upward-dump three bolt exhaust manifold and the special thick spacer that spaced it out from the head and corrected an angle problem. Those are now unobtanium (I have a spare set that can only be pried from my dead, cold fingers) but would make the adaptation of any modern turbo a piece of cake. Check out the pics the see what this looks like. Now that we are fifty years (!) past the introduction of that option, this is all history but is instructive of what to do and not to do. And there are modern fixes to those deficiencies and from one owner I knew who went to the trouble back then to fix the ignition problem, the 152 could perform! But I do agree with Robert in that a modern turbo is the way to go, but I'm stubborn and will soldier on with my plan to use an original unit that's been modified.

Edit: I was called away while typing this and Robert added his reply. You really need a modern ignition. Unless you run efi, you can do a crank fire conversion like I did. This is vital because you need the equivalent of vacuum advance for normal driving - which gives you your fuel economy, plus the engine runs cooler - plus timing retard when under boost. I've done this conversion twice and it really isn't all that difficult to do. The reason I push this for a turbo setup is that you have the unique problem of needing advance and retard. For a regular hop up or something, pertronix or performance distributors are sold here and all that stuff is good, but to my knowledge there is no canister available that will provide both actions.

Stepping down off my soapbox.
Last edited:

Robert Kenney

Super Moderator
Ya, I forgot about the ignition.
I'd run a pertronix module in the oem dizzy. Choose a msd box hopefully with the boost retard function and trigger it with the pertronix .


New member
Thanks for the two resource links, I'll be reading through those in the next few days. Haha don't worry Robert, IH parts is getting a ton of my business even if I get the turbo and some engine/ignition parts elsewhere. I'm already budgeting for their lift, disc brake kit, some fiberglass panels, possibly the engine kit, so they'll be seeing a few grand from me over the course of a year.

Do you know if the silvo-lites the ones that come in the ihparts engine kit? If not I'll chat to them about it when I order my lift in a week or so.
thanks for the two resource links, I'll be reading through those in the next few days. Haha don't worry Robert, IH parts is getting a ton of my business even if I get the turbo and some engine/ignition parts elsewhere. I'm already budgeting for their lift, disc brake kit, some fiberglass panels, possibly the engine kit, so they'll be seeing a few grand from me over the course of a year.

Do you know if the silvo-lites the ones that come in the ihparts engine kit? If not I'll chat to them about it when I order my lift in a week or so.
Jeff can get those pistons.


New member
I stumbled upon this thread which is convenient because I am tossing around the idea of turboing my 152 as well rather than ripping out the motor I put blood, sweat, tears, and money into rebuilding. I do have a couple of questions though...

1. When trying to select a turbo should I go with the manufactures horsepower goal rating or engine displacement recommendation, or is there some other way I should be selecting a turbo.

2. Which would be better/easier & cheaper blow through or draw through turbo setup? From what I have read outside IH forums everyone says to convert it to fuel injection and do a blow through setup and I am not really prepared to sink that much money for a 50ish horsepower gain!

3. Any carb/ turbo recommendations I am not scared of fabrication to make something fit just need help trying to figure out what that something is.

P.s. My Scout is a 63 Scout 80 with a 152 that I rebuilt with flat top pistons and new everything, its in the readers rides section somewhere to include the engine buildup.

Also need to say I love this forum it has saved me more times than I can count, thank you:icon_xd: