Only one turbo?

You need more torques down low....I suggest going compound boosted supercharger/turbo for this tire frier oddball.

http://www.lsxtv.com/news/granatelli...early-1200-hp/

 

Although my spider-senses are alerting me of sarcasm, the thought of compound boost has crossed my mind.

But... Whipple superchargers don't like to be force-fed. So the whipple is out. I'd put a ported lsa blower on it, and compound that with a turbo(s), but the only way to mount the lsa blower on the cathedral port heads is with an adapter... And I don't know if said adapters can handle ~30# of boost.

I don't trust non-6-bolt heads to handle 30psi, to be honest. Not even with the thicker deck on the AFR castings.

Compound boost would be cool and fun, for sure. And it would really fit in with the special and unique snowflake theme behind this build.

But I'm thinking just one big, t6, twin scroll, turbo mounted front and center. Fed by a set of up/forward, 180° "bundle of snakes", stainless steel headers.

Since the beginning of this entire absurd idea, a big single turbo has been the plan. I figured that the undersquare architecture/4" stroke would give me all the torques I need down low, and the aforementioned big single turbo would take care of everything from 4-7000rpms. Once again, spitting in the face of convention, I chose a big single turbo just so I would have to rev my "rpm-inhibited" stroker.

 

Guessing sarcasm, you don't need all that much "torques down low" when you have a 3000lb car that's geared correctly and/or with the proper stall.

 

That's why the big single turbo made sense to me. Or at least as much sense as the rest of it.

A long stroke six liter will already provide enough torque to make finding traction difficult, even without boost. So having a big single turbo that doesn't really wake up until the truck is moving won't be a bad thing at all.

I already plan on getting in touch with mister Ron Sutton, to design a proper decoupled 3-link rear suspension for the S10.

The decoupled top link has specifically calibrated dampening bushings to soften the torque delivery and not upset the tires. So that should help, a lot.

My plans to use a 3-link suspension is also another reason why compound boost is out of the question. I'm pretty sure you need a 4-link for that sort of torque... The sorts of torque associated with a long stroke, boosted, nine liter motor.

Yes, nine liter motor. Compounding boost through a positive displacement blower essentially just adds displacement to your engine, and you choose the turbo(s) in accordance to that "new" displacement.

I believe it works out to something like the displacement of the blower multiplied by the pressure ratio of the blower, added to the displacement of the engine.

But I'm not compound boosting this undersquare six liter, my S10, or anything else, for that matter.

 

I don't think it will set the world on fire or anything, but it's your money so do with it what you will. If you're not happy with it, at least you will have the crank and rods to build a 383 or 408. The displacement is what gets you torque. The top end basically dictates where you make that torque.

 

It would be ok in a truck used for truck purposes

 

Well, last time Tony said anything about his 205's, he mentioned getting it to flow 300cfm. That's awesome. I trust a set of mamo-fied AFR heads designed specifically for the 3.78" bore to make torque everywhere it can possibly be made.

Although the Holley intake is damn sexy, being damn sexy doesn't win races, so I think the mamo-fied Fast RT 102/102 has to happen.

So, in summation, a fully forged six liter rotating assembly, mamo-fied AFR205 heads that flow 300cfm ON A 3.78" BORE, mamo-fied fast rt 102/102, and a t6 s480... What about any of that sounds like failure?

Why would it only be good for doing "truck things"?

I'm going to put it in a truck and do what I want "truck things" to be in it... A 3000# S10 with a road race/pro-tour suspension, cage, and nitto drag radials.

 

205's flow 300 on a 3.90 bore for an ls1, the engine they were designed for. A 3.78 will flow LESS cfm than that which is what we've been telling you. Put that head on a 3.78 bore and it may only flow 280, but it on a 4" and it will flow 315. The size of the bore ultimately dedicates what the head can flow. Why this eludes you after 3 pages man I'm not sure.

Hammers point was that since you will be choking the heads it will make good tq down low but fall off up top...which is what we have also been telling you

 

Tony Mamo is building a set of heads specifically for the 3.78" bore, based on AFR205 castings. And he personally said that he is at 295 or 297 right now, and is going to get 300cfm out of them flowing in a 3.78" bore.

So, if you put heads literally designed to be used on a 3.78" bore, on a 3.78" bore (like they were meant for), are you still "choking the heads"?

I have already said that I know and understand that they would flow more on a larger bore. I get it. And I don't give a ****, because WE AREN'T TALKING ABOUT A LARGER BORE! This discussion is about a 3.78" bore. The end. For the sake of this discussion, no other bore size is a possibility or on the table for consideration. Literally making that little reoccurring tidbit of information about how the heads would flow more on a larger bore useless. I know they will, and I still don't care.

I swear I mentioned wanting to specifically use the small bore blocks for their thicker cylinder sleeves. What part of this are people not understanding after three pages? And I know the ls2 and ls3 have thicker cylinder sleeves, but then we are talking about a much larger displacement than I am looking for. I said I was going to draw the line at six liters. So I will take the thicker than ls1 sleeves in my 3.78" bore block, and gladly have a 359 instead of a 383.

And I don't want a 400+" engine. I don't. The whole thing that started this was I wanted to see what the smallest displacement LSx would be with a 4" crank. That led me to the undersquare 359.

And here we are...

 

It was brought up earlier that the increased stroke would add to crankcase windage, as well as piston ring flutter.

These are easily addressed issues with a crank scraper and a vacuum pump. Both of these are items I already plan to use.

As well as check valve oil squirters. Bo law performance makes a nice kit for the ls motors.

 

None of those pieces can fix your rod angularity..
Why don't you go 3.81" on the bore and hook a set of 6.25" rods to a K1 3.90" stroke crank for a total of 356 inches but with a 1.6 rod to stroke ratio.
The piston will be entirely in the sleeve at BDC.

 

Yes, both a scraper and the vacuum pump just address the symptoms, not the cause. But both will be used, regardless.

As for the proposed 356... I wasn't awares. I do absolutely like the sounds of that, and will investigate further.

Thank you for bringing it to my attention.

 

How do you plan to hook any of this torque N/A or turbo in an *** light truck ??
The aluminum engine benefit helps but the T6 snail is about sixty pounds all by itself.
Fill your tail gait with lead or concrete....

 

I haven't gotten that far, yet.

I'm hoping that smart gearing, a properly designed decoupled 3-link rear suspension, and an equally well set up th400 will give the rear tires a fighting chance.

I may not need the turbo, depending on what it does naturally aspirated.

If I can afford to skip the wcch stage two heads, and jump straight into the mamo-fied mms205/fast102rt top end combo, it will probably be plenty adequate without boost.

I like that 3.9" crank with the 6.25" rod. It makes for 350ci with the 3.78" bore. And is a much more favorable rod ratio of 1.60, very close to the factory 6.098 rod and 3.66" crank of 1.66.

And according to the Wallace racing online calculator, the mamo-fied mms205's, flowing 300cfm, can support a 350ci engine between 7000 and 9000 rpms. That's fun.

Just need to figure out pin height and find pistons for this combination. I'm sure the K1 forged crank and rods can be found without too much trouble.

 

Summit carries the crank and rods can be had anywhere. I buy from Competition Products in Oshkosh but that's only cuz they're local to me with decent pricing. You're looking for a piston compression height of 1.05" or 1.065" which ends up out of the hole (.010"-.025") but you can get any thickness Cometic gasket needed to set your quench clearance. Arias has these in stock but only for the 3.905 bore which you're not wanting to bore .125" over or have a 374 incher.
I thought Tony had recently gotten over 290 cfm from some hand ported 862 castings that he put a 1.96" valve in.
Trick Flow 205s are also pretty hard to beat and come CNC'd, use stock size 2.0" intake valves with a 1.57 exhaust, and they're stock rocker compatible with the powdered metal valve guides.

 

I knew the stock truck castings could be made to flow enough to support six liters, even on the small bore. And the price of those wcch stage two heads is hard to beat. That's why I brought using them up.

I was originally looking at the trick flow 205's, and was pretty set on using them until I stumbled upon the heads mister Mamo is building for the small bore.

Any of the three (wcch, mamo, or tfs) will likely be enough to make finding traction difficult.

PS. The sub-3000# platform is one of the big reasons that I have no desire to exceed six liter of displacement. I'm perfectly happy with the 350ci given by the 3.78" bore and 3.9" stroke. That's fine for what it's going in.

 

Trickflow 205's are 284 intake, 228 exhaust at .600 lift on a 3.800 bore.

 

Yeah, I really do like the trick flow 205's and I was planning on using them until I saw Tony Mamo was building a set of dedicated small bore heads.

The tfs205's were going to be what I upgraded to from the wcch stage two heads when I added the turbo.

Now I'm going to try go straight to the mamo-fied top end, and may not need the turbo... Or at the very least, I won't be able to afford the turbo for a while.

Which is fine, because I wanted to drive it naturally aspirated for a few years, anyways. I will gladly give up the displacement for the better rod ratio, so I'm leaning towards the 3.78" bore and 3.9" stroke with the 6.25" rods.

 

Q1. Can anyone elaborate or explain the effects of small bore/long stroke on cylinder pressure?

Cylinder pressure drops dramatically after it peaks, regardless of which cylinder it is in.

A long, narrow cylinder will experience less change in volume, per degree of rotation, than an oversquare cylinder.

Expanding volume decreases pressure on its own. Now combine an expanding volume with the dramatically decreasing cylinder pressure, and the problem is compounded.

An undersquare cylinder adds to this phenomenon in a less severe manner than an oversquare cylinder. The Heywood book of fundamentals says, in a long stroke engine you get a force that decays away slower as the volume change per degree of crank angle is less.

Therefore, an undersquare engine, in theory, should actually make better/more efficient use of any available cylinder pressure.

Even with the added distance/friction, the undersquare motor is using more of the cylinder pressure to rotate the crank.

Q2. Am I correct in that the same amount of force applied to a smaller area equates to an increase in pressure? In this particular case of a smaller surface area piston receiving the same force as a larger piston with more surface area.

Pressure equals force divided by area.
P=F/A

So if the area decreases, yet experiences the same force, pressure has to increase... Right?

 

It's my belief that you don't want the power stroke taking a bunch of degrees (crank rotation) to force the piston down. An engine with a low BSFC has a faster burning more explosive pop. I call it "kicking the slugs" as opposed to a leg press or pushing the object.
The more efficient an engine converts potential energy into kinetic motion, the less emissions it will produce, the more power it will make, AND the less ignition timing advance it will need to make peak power.
Old school dome piston RAT motors with big chambers need 42-44 degrees of lead, old school MOUSE motors usually liked 36-40 range depending on piston/chamber design, LT/Vortec stuff about 32-35 range and most of the LS stuff is around 22-27.
The primary ring is also much closer to the top of the bore than ever before on production stuff.......this maximizes the compression as well as minimizes the dirty unburned hydro stuff.
Also keep in mind that the speed of the piston is not believed to be a constant for a given rpm.
Deck heights do dictacte the rod to stroke ratio and long stroke/short rod stuff accelerates the piston at and near TDC (slower through the bore). Big bore short stroke i.e. long rod (better r/s ratio) dwells the piston at and near TDC longer which helps to build upper combustion chamber heat (transformation of energy) but then is quicker through the center of the bore.
Both of these scenarios also PULL on the induction system differently due to the piston speed on directional change.