does anyone make high compression pistons for a 170

-
andrew3408

andrew3408

1969 Plymouth valiant
Joined
Nov 24, 2014
Messages
107
Reaction score
19
Location
Republic,mo
been searching around the web and i can't find any pistons for a 170 looking for about a 10.5 compression out of the 170. so does anyone make any after market pistons for a 170?
 
No, not off the shelf. Big piston companies will make anything you want though in a custom piston.
 
I ran 170 @ 198 /6 at speed trials many years ago and used Jahns in various cr's.
They were heavy but durable. We twisted most of them to 8k and never lost a piston or lower end. Took a long time to sort valve train issues though.
Good luck
 
Have you checked the Mopar 2.2 piston? a .040 over would fit a std bore 170 or bore to a .060 over.
 
ok guys thanks for the info.. ok if i use the stock pistons which i believe for 69 was 8.5 comp... i got a cam pickout at cliffords to put in this engine my question will the pistons need to be notched for this cam specs below
Mechanical cam package
.498” 280 / 290 246 / 256 to ROUGH IDLE. 2,500 to 5,000 VALVE LASH (.024” Int / .026” ex.
 
First of all, don't buy squat from Clifford. You'd be better off donating the money to your favorite charity, because you ain't getting anything worthwhile from them.

Second, go over to slantsix.org and read for a month. Or twelve. Those guys eat sleep and breath slants. Run your ideas by them, they'll set you straight quick.
 
nm9stheham said:
According to this, notches would be needed at this lift/duration for some level of head milling:

http://www.slantsix.org/forum/viewtopic.php?t=55723&view=next

Charrlie S would likely know.

Is this engine for the street or what? Auto trans or manual? With stock CR and this much cam, I would expect this to be doggy at low end. (Have a not looked at the LSA however.)
Click to expand...

It Will be for the street mainly with a 727 with a high stall and 355 gears and as far as the CR i would liketo have 10.5
 
oh also if i could find the hyper pak type cam they run back in the 60's with the 170 i would be happy
 
Get ready to use race gas with 10.5 compression with no quench and an iron head.
 
andrew3408 said:
It Will be for the street mainly with a 727 with a high stall and 355 gears and as far as the CR i would liketo have 10.5
Click to expand...

That 727 is completely unnecessary, because a 904 will cost you far less parasitic drag and you'll likely NEVER break it with a 170.

Don't throw away all that horsepower for nothing...

Also, a 904 can be had with an OEM 2.74:1 first gear, something the 727 never had.
The 170 will like it...:D
 
RustyRatRod said:
Get ready to use race gas with 10.5 compression with no quench and an iron head.
Click to expand...

I believe it's been done before, they just ran a large enough cam? And isn't the 170 pretty much a zero deck engine? It may be a whole lot easier to achieve quench with a 170 than a 225

andrew3408 said:
oh also if i could find the hyper pak type cam they run back in the 60's with the 170 i would be happy
Click to expand...

Very outdated cam. I'm sure someone who knows more than I do could recommend you a better cam. Since the 170 isn't a monsterously undersquare like the 225, a more v8-esque cam may work well.
 
Brandon Weaver said:
I believe it's been done before, they just ran a large enough cam? And isn't the 170 pretty much a zero deck engine? It may be a whole lot easier to achieve zero quench with a 170 than a 225
Click to expand...

Zero quench? First, I think you need to read up on the terms you're throwing around. No offense, but you sound like a kid trying to bench race without a bench. Again, no offense. We're trying to help people here. Nothing personal.

Now, by the time you mill the head enough to achieve proper quench (and it AIN'T zero), the head is either going to be so thin it will be unusable, OR you will have hit the water jacket. Sorry, those are just the facts. Can you mill the slant head? Heck yeah and they can stand a LOT of milling, but there isn't enough there to create a quench head. In short, you cannot achieve quench in a slant. It is not a quench engine.

Has 10.5 compression been used with iron heads and no quench on the street with pump gas? You bet. Choosing a camshaft with a late intake valve closing event causes the cylinders to begin building pressure later in the stroke and thereby diminishes cylinder pressure in comparison to a camshaft with an earlier intake closing event.

However, with a slant six, all you have is six cylinders. If you run a camshaft large enough to allow pump gas with an iron head and at 10.5 compression, it will be a dead dog on the street. You will literally need a 3500-4000 converter and 4.30 gears at a minimum and even then it's going to run like stink from idle to 3500.......RIGHT where you want extra kick in a hot street car.

Slants are very peculiar with camshaft selection. It does not take very much to over cam one. Best thing to do is spend your money and mill the head about .100" or so. Get compression up to close to or right at 9:1. Have it professionally ported. Choose a camshaft that will give you the best performance where a real street engine will see the most RPM. Probably in the 1500-5500 range. A nice split pattern cam with around .480-.520 lift and no more than 236* duration @ .050 ground on a 108 or even a 106 LSA. If you go with the 106 LSA, I would keep duration @ .050 to no more than 226 @ .050.

Even so, it will still be somewhat "light switchy" as far as power. If you want a broader torque curve, raise the LSA to 112. That will give it more bottom end and a flatter torque curve at the expense of a little loss on the top end. That's what I would do. You will have better results.

Keeping compression low, will assure it will successfully run on pump gas even in the hottest summer months idling in traffic. Raising compression one whole point only sees an increase in power between 1-3%. With the slant, it's on the low end of that spectrum. Good smart bolt on parts choices such as cam and having the head milled and ported with larger valves installed will net you much more of a power increase than raising the compression too high for pump gas anyway.

Build yours like you want. No need to listen to people who have done it over and over for thirty plus years. That makes too much sense, but this fella needs correct information, not just something repeated from V8 builds that won't work with the slant. Lets try to keep it on track as much as possible.
 
i don't have a 225 the car has a 170 in it and it shorter stroke make it a screamer? 8000 + rpms now if someone wants to donate a 225 i will take it..lol
 
OK, will do when I get that spare one! Just seems an easy way to get torque/HP..... keep your eyes and ears open, you might just stumbel across one cheap and have a way to spend less.

BTW, I raced a screamer engine for many years that was good for 8000 rpm + (Opel 1.9L) and that had the large bore / short stroke combo, big cam and carb and all that; great at top end but nothing below 4k. Light switchy' to the max as RRR puts it and very much like a 2 stoke moto engine with nuthin' at low RPM. I COULD drive it on the street but was not a 'streetable' combo. And for the racing use (rally) the 4000-8000 RPM range was too narrow; extending the RPM range down to 3500 with some smaller sidedraft carbs was well worth it in actual usable performance, and I should have done more for the low end in retrospect. It would end up in no-man's land in the tall 2-3 shift; not slow enough for 2nd gear and too slow to be well up on the torque curve for 3rd, and stage times suffered on some twisty mid-speed roads. My later Plymouth Arrow 1.6L with a different approach for much better mid range torque was actually quicker with an excellent 1500-6500 rpm range with usabel torque, and did not have any gearing 'dead-zones'. (But everyone told me that they knew the sound of my Opel engine coming through the woods so I guess I got SOMETHING out of it LOL...)

For street, you are wise to take the advice to go the other ways. Save the high stall, high RPM, max HP approach for a strip engine and concentrate on good low and mid-range torque; good mid range HP will flow from that and the car will be snappy and FUN to drive. Head out east from where yo live and driving a good torque-engined car in the Southern Missouri hills will be a great driving expereince, and with the torque ready to go, you will always be ready to attack a corner and hang the rear end out, not backing off of a hard corner because you don't know exactly when the 'light switch' will come on.

And low RPM engines attract the police less readily....
 
RustyRatRod said:
Bill, why aren't you hollerin TURBO here? It would be the smartest way for him to go.
Click to expand...

No, the smartest way for him to go is to dump that 170 for whatever he can get for it, and replace it with a 225, one way or another. A 225 will make as much power, naturally-aspirated, as a turbocharged 170, I believe, and will be a heck of a lot cheaper to build and with a lot less trouble, and the learning curve will be considerably more gentle. That's a lot more important than being able to twist the motor 8,000 piston-breaking rpm.

I LOVE the idea of turbocharging a slant six, but the application has limited usefulness... and, this is not it.

Just my 2-cents...
 
Well knock me over with a feather. lol
 
I'd have to disagree with you bill. Small cubic engines benefit greatly from boost! While everyone is quick to say "no replacement for displacement", that isn't entirely true. Boost is the replacement!

I think what's been prevaliant with most I the slant turbo builds is simply overcomplication! For a mild street build I don't see the necessity in a lot if what goes on with these turbo builds.

Take a stock 170ci that's rated at 8.5:1cr, use a Garrett turbo off of any of the TII intercooled turbo dodges. Don't use the tiny Mitsu that came on ' 88 and up non intercooled turbo dodges. They were undersized even for the 2.5 they came on.

Exhaust side go with a 2.5" out the back. Intake side go with th Super Six 2bbl intake and a weber 3838DGAS. This is a great carb that can be made to use for boosted applications easily.

Intercooler shouldn't be necessary when running less than 8psi. I'd use a small air to air cooler and crank the boost up to a solid 10psi.

This setup should be reliable and I imagine it would make near 180-200bhp easily!
 
You must log in or register to reply here.
-

Back
Top