Porting turbos?

[johnl]

I've got a Turbonetics Super 60 and I'm concerned that it may not be big enough, as compared to T3/T4 50 trim hybrid; worried I bought the wrong one - my HP target went up since then.

The engine is not 2.5; it is a 1985 2.2 non CB stnd bores, with 52mm TB, ported 2 piece IM, ported iron EM, 3" SV and exhaust, ported bath tub head with deep dish swirl head pistons - low compression, +1mm valves, slider cam.

I'm thinking that the hybrid might be just a tad large for the 2.2 (as opposed to a 2.5) while the Super 60 might be a tad small for the manifolds, head and exhaust. Am I talking nonsense?

What can be gained in terms of porting the turbo? What to do? What not to do? Can porting bridge the gap to the hybrid?

[cordes]

What are your HP goals?

[johnl]

What are your HP goals?
350 - 400

[Directconnection]

crank or wheel hp?

A s60 can do 350 crank hp... but maxed out and you'll need a really good intercooler.

[8valves]

The turbo won't make it there, but porting will help slightly.

S60's are supposed to run out of juice at 300 or so, maybe a bit more. You can port/smooth the inside of the turbine housing and get some great gains from that as long as you match it to the mouth of the exhaust manifold, but it's just not going to have the compressor side I'm afraid.

Good luck getting to those levels with stock pistons reliably :)

Aaron Miller

[johnl]

Aaron - good one - about the stock pistons.

[8valves]

Aaron - good one - about the stock pistons.

No no, I wasn't trying to be a smart ---, seriously, good luck having them be reliable at that level! I was saying good luck to you, as in it's possible I just don't think it'll be too terribly reliable at those cylinder pressures... not a whole lot of room for error at that point unfortunately. Once again though, and in all seriousness, good luck! :)

Aaron Miller

[cordes]

I agree with Aaron that the S60 wheel just won't have it to make that kind of HP. It would be huffing and puffing engouh to blow your house down, but with the mods you would need to get close to your goal with the S60 they hybrid would make much more efficient power.

[2.216VTurbo]

Aaron, I have seen the kind of projects JohnL gets involved in, rest assured there will be quality forged slugs in there;) He just got a bit premature on his turbo selection, bought it before he knew what he wanted from the car...

John, if you need a good home for that S60...

[johnl]

Thanks Alan - But . . . . I do have standard bore Mahles in it. So . . . . maybe I ought to just settle for 300ish for this go round. In my mispent youth I had nothing but back experiences with forged pistons in two strokes and I learned that OEM castings are often preferable.

Too many manufacturers of forgings sell, or sold, C**P. Too often they are unwilling - too cheap - to do the development work, in terms of fine tuning the shape - the taper, the barrel, the alloy, and so on.

I have no doubt, however, that at least one of our vendors, HAS done that development - by self funded trial and error and by diligent solicitation of feed back from competent customers; and, by that process has arrived at a shape and dimensions that works well.

Here is what I wrote somewhere else:

"You have to ask, why do OEMs favor cast pistons?

They do so because cast pistons, RUN UNDER OEM CONDITIONS, last longer.

Why do they last longer - tighter clearances than forged - especially at start up and on the cold engine/no warm up/stomp on it run to the 7-11 for milk.

The longevity of an engine's piston/cylinder seal depends a lot on squareness to the bore - how square the piston and its rings run in the bore. The loose tolerances of forged pistons (especially at start up) allow too much rocking in the bore. OEMs want to get 200,000 miles out of a set of pistons and bores. When that is your priority, it is NOT good to have rings that constantly get their corners knocked off by a piston that fails to hold the rings square to the bore. Same thing applies to the bore - ya got sharp ring edges gouging the bore because the piston won't hold the rings square to the bore. Simply stated - the tighter the clearance, the longer and better it seals.

To maximise concentricity and fit to the bore, pistons are tapered from top to bottom, smaller in diameter at the top and bigger at the bottom. They are also oval, narrower across the pin dimension and wider at 90* to the pin. These shapes adjust for the greater expansion caused by the greater amount of expanding metal in those areas. Concentrity/fit enhances the ability of the piston/ring combo to seal and more importantly, to transfer heat to the bore walls.

Ring seal is a priority. Blow by - fire/carbon blasting past the rings - contaminates/damages the bore and ring surfaces and inhibits the ability of the rings to transfer heat from the piston to the bore. Rings with their corners knocked off by a rocking piston have LESS SURFACE AREA to transfer heat with as compared to rings riding in a piston that maintains squareness to the bore. Forgings are naturally loose, compared to castings.

The OEM Mahles work as well as they do because of their design, their alloy and their shape are a balanced combination that holds the rings more square to the bore, even in a cold engine. Their high silicon content alloy, however, CANNOT take the hammer blows of detonation as well as the soft alloys of the forgings.

A forging that is well designed in terms of expansion/shapes/clearances, and which is warmed up - fully expanded to its operating dimensions - will run just as tight as the Mahle casting AND will deliver equivalent ring sealing AND will suffer more detonation.

Tuning errors. That is why forged pistons are preferred. Forged pistons will suffer detonation abuse that cast pistons cannot. Castings crack, forgings do not. Forgings, on the other hand, having a lower melting point, they more easily will smear and stick/seize to the bore when a blowtorch of blowby gets past the rings. Again - proper clearances/shape/taper/barrel are critical.

When metallurgists invent a forgeable alloy that has the low coeffiecient of expansion of a high silicon content casting alloy, then we will have the best of both worlds and this debate will be over."

[johnl]

More of my rant - from somewhere else - maybe this belongs in engine/block forum?

"Many of the most successful engines in motorsports use cast pistons. Look at any two stroke road racer - 100 % cast pistons. They are just much better at consistent sealing. Poor ring seal begins a cascade of events that leads to failure.

Most racers have no expectation of long life from their race engines; the superior ability of forgings to withstand detonation outweighs their inferior ability to maintain ring seal over the long term.

Read your pistons when you take an engine apart. Look at the pattern of carbon on the skirt below the rings and in the area around the circumference just below the oil rings. Usually a forging is not as clean as a casting. Cleanliness in these areas, in a high perfomance engine, signifies real power. It shows that the rings are EFFECTIVELY transferring the heat through the rings to the cylinder wall. The piston below the skirt is not hot enough to carbonize the oil that's on it. It shows that there are no blow torches of blow-by polluting/interrupting the ring face/cylinder wall interface or turning vital piston and wall lubrication to carbon. These are some reasons why cast pistons can make superior power.

But again, forgings, especially ones whose barrell and taper and cold clearance have been well developed, will seal just as well when at operating temperature.

Another thing, OEM castings generally are lighter. Especially when you look at the cheap forgings where minimal effort is made by the manufacturer to lighten them. A common cheapo trick is to make one forging die which is big enough to make a .060 over piston but then they also sell it for Stnd bores. they make the wall thickness of the skirts thick enough so that it can be turned down to Stnd. In its Stnd configuration, its weight is OK but in the .060 version the piston walls are too thick and heavy. If there is enough demand, and enough *****ing from the customers, then they might make two dies. Or, they may not offer a Stnd bore size at all, leaving that market niche to the OEMs. The same trick happens with cast pistons too though."

[Directconnection]

The turbo won't make it there, but porting will help slightly.

S60's are supposed to run out of juice at 300 or so, maybe a bit more. You can port/smooth the inside of the turbine housing and get some great gains from that as long as you match it to the mouth of the exhaust manifold, but it's just not going to have the compressor side I'm afraid.

Good luck getting to those levels with stock pistons reliably :)

Aaron Miller

It has been done. 291 wheel HP (23psi) by Jon Genesky's CSXT a few years ago. Stock cast pistons to boot. He later ran the turbo for all it was worth to run solid high 11's. NPR cooler and stock G-head w/2-1/4" SW.:whip:

[GLHSKEN]

John,

Wiseco's have the clearances you are looking for. .0035 is the recommended install. The ring lands were also beefed up by as you said proven methods.

How about an Omni putting 406/467 to the wheels with them without a hiccup. Engine has been together for 2 years and made literally HUNDREDS of passes in the 125mph plus range.

No matter what, the head will be your issue here. If it is not ported, you will NOT be happy with the turbo's response if you go larger. As with everythng in life, there are tradeoffs.

[2.216VTurbo]

Yeah John, what about that head? You have been keeping this project a little bit under your hat haven't you;) If that head hasn't been ported maybe you should send it to one of the local porting specialists... I am just finishing a 16V TC Masi head with oversize valves, new guides, springs, unshrouded valves and reshaped chambers. I have ~25 hours in it and another 3-4 should get me assembled and ready to run:evil:

[GLHSKEN]

Uh-Oh, the so-cal boys are conspiring...... Look-out everyone...

[johnl]

OK Alan - here's pics.

If I'd have known better, I probably would have handed the head off to Pat. Basically, each port is higher and wider and the floor and the short turn radius were barely touched. No flow testing. Just used an inside caliper to ensure consistent dimensions, port to port. Finished walls with straight and curved files to make the walls flat/straight.

[johnl]

Forgot this one.

[GLHSKEN]

You should spin a T3/4 50 trim just fine

[mcsvt]

Nice job :thumb:

[show-off]

I put down 251 whp @ 18psi on the Super 60. Wastegate issues kept it from boosting in high mode of 25psi. I was really rich at 10.5:1 A/F ratios.

I was killing cast pistons at this level last year (it was tuning errors)....Wiseco's and a proper tune fixed that problem too.

[8valves]

It has been done. 291 wheel HP (23psi) by Jon Genesky's CSXT a few years ago. Stock cast pistons to boot. He later ran the turbo for all it was worth to run solid high 11's. NPR cooler and stock G-head w/2-1/4" SW.:whip:

Right... which it peter'd out after the 300 mark, and John is saying he wants 350-400, which is why I said it won't make it. I think you missed the 350-400 whp part of this.

Aaron Miller

[Directconnection]

Right... which it peter'd out after the 300 mark, and John is saying he wants 350-400, which is why I said it won't make it. I think you missed the 350-400 whp part of this.

Aaron Miller

If I recall...his post was 350-400hp... not wheel. So I assumed he meant crank hp. If wheel hp, then yeah...no way.

[johnl]

Thanks to all for helping me think this through. A year ago, when I started this project, I just wanted to modify the parts that I had. I also was thinking more about roadracing and autocross than drag racing.

So, I started off with a target of 300 WHP. Think I'll stick to it. Since I'm a newbie, hitting that number will be tough enough anyway.

Trying for 350 WHP by putting a hybrid on top of the Mahles would be asking for trouble.

Also, I'm running a Ramsdell 525 hybrid with moly plate and Lambros girdle and Shelby posi; the decision to retain the 525 assumed the 300 WHP target too.

There's always next time . . . .

Let's see "2.2 CB, forged crank, rods, hybrid 568, no I know 2.4 . . . . ."

[2.216VTurbo]

:lol:

I don't exactly think of yo as a newbie John, you've built what 25-30 cars over the years?:thumb: TD's are a bit fresh to you but you are a quick learner, some guys in our SD club have been at it 15+ years and they still haven't learned a thing:p

[johnl]

Thanks Alan I love flattery, bought you a drink or two.