Inliners International Forums General Discussion Blown and Injected snowman4839 turbo build

Snow,
You really need to sit down and plan out your build. Similar to what you are doing now. Go thru the ideas and whittle thru them, weighing the costs vs benefits. And how they line up with your final objective.
I personally like the idea of the MS system. It is very flexible and could be fully used at a later time. Easy to program too. The timing control it will give you is invaluable.

The fuel scavenging issue is a big one. I ran into it with my Turbo 292. Look at the firing order. 153624. Notice how 2 fires and 2 puts later 1 fires? Here is where it happens. 2 gets a full charge and 1 gets a partial charge. Same happens with 5 and 6. These cylinders fire too close in time to each other and therefor rob fuel charge from the lagging cylinder.

A good throttle body system will mask this and not be much of a problem until about 500 HP. Same with a carb system.

I thought I had been doing a pretty good job of that. I just happened to include the MS3 system because it was a great idea assuming it would work as expected. But now I'm going back to my original plan. Turbo cam -> roller rockers -> new valves -> forged pistons -> J&S system -> get it running and broken in -> drive it awhile -> work in alky injection -> profit. Probably do some porting an polishing while it's apart.

I'll get my timing control out of the J&S system just as well. Even as you've been saying it'll be more precise since it's by cylinder.

I don't see TBFI worth the extra money when I already have my carb setup. I already have my wideband installed for tuning. Had pretty steady mid 11 AFRs at full boost if I remember correctly. I can always drop it more if I need to The J&S will help me get my timing perfect. Those are the two major ingredients that I will have a pretty good handle on.

I think I'm on the fast track to a great motor.

Snowman,
If you do decide to get a J&S, my friend (his website) http://www.american-pi.com/corvair/corvhome.html
http://www.american-pi.com/safeguard/safeguard2.html
would be more than happy to tell you how it all works & how to hook it up & which one to purchase.

You can purchase it through my friend or direct from J&S website.

J&S features.
A new, faster microprocessor is used .



Nitrous retard is built in and fully adjustable. Also can be used with turbo engines to heat up the exhaust for harder launches and quicker turbo spool-up.



Cranking Retard is built in and fully adjustable. This is especially helpful for turbos, high compression engines or non-turbo engines which run large amounts of static ignition timing. It also makes for easier starting in colder climates and/or higher elevations.



Preemptive Boost retard. Fully adjustable start settings and rate with test points.



Electronic vacuum advance. Fully adjustable start settings and rate with test points.



Selectable Rising or Falling Edge Input Trigger.



Selectable Rising or Falling Edge Output Driver.



Magnetic Pick-Up Trigger circuit is now built-in and fully configurable.



Two SoftTouchsm Digital REV Limits are now built-in and fully adjustable.



New knock sensor is smaller and has a lower profile. You can mount it on any cylinder bolt hole location which uses a 1/4-20 or 3/8-16 thread. It is small enough to be mounted right beside and under the carb.


MBHD

MBHD - I just emailed him all my questions and concerns.

Yeah, I didn't mean to fully de-rail the build plan posts. I'm advocating using an MS2 for ignition control only, for at least any near term planning. And CERTAINLY weigh the cost, options, ease/hardness of installation between both the MS and J$S systems.


Fuel side control I'd say do way way down the road when you have a good solid running, reliable, engine. That way if you have issues with it running EFI'd, you'll know it's the fuel delivery and not the ignition giving you issues. One piece at a time, don't eat the whole elephant in a single bite.

*As a slight side note, with the MS3 and sequential or semi-sequential(MS2?), the cylinders that run lean due to scavenging can have their injectors dialed up while the rich cylinders dialed down to suit the scavenging. With out per cylinder AFR or EGT monitoring it might be difficult to get exact but using numbers like 10%-15% more/less probably would get you in the ballpark. The increase/decrease is programmable by rpm and load (it's a table), so it can be programmed to adjust for more scavegening at higher rpm/load and low to no scavenging at lower rpm/load.

Cool, he will answer any of your concerns. Very knowledgeable person & can tune any EFI system.
FAST, Holley, Tuner Pro Code 59 FOR GM ECU's, Megasquirt, etc.

MBHD

So if I use that O-ringed felpro gasket, ARP rod bolts, forged pistons, the J&S system, moderate boost, and eventually meth injection shouldn't the engine be pretty much bulletproof for quite awhile? I've eliminated weak pistons and detonation which I imagine were the only two problems I faced for longevity of engine life.

Both the pistons and stocks rods would be forged. The last two things I can think that would the crank and the main caps. At what point would it be worth it to get a ARP kit for the mains? And up to what HP would the stock crank support? Is it worth it to do any crankshaft work like lightening or polishing?

It is always a good idea to side grind polish & shot peen your con rods, & of course magnafluxed.

I would not worry about the crank or the main cap studs.

What HP & RPM are you planning on spinning it to?

Stock crank has seen 1000-1400 HP in Brazil.

The thing that is great about a turbo engine, it is easier on parts, you do not need to spin to 7000+ RPM to make great HP & torque.

But don't forget, if your tune is off w/a turbo engine, it can take out your pistons in a flash, that's why I say tune, tune, & then tune some more in small increments & raise the boost level in very small increments also.

For what your are going to do, I believe 400-600 HP Range can be achieved. Believe me, enough to spank a lot of those pesky V-8's

MBHD

Yeah, doesn't matter what your pistons are made of, a bad tune under load will destroy them in a heartbeat.

7 mains make the bottom end pretty tough. The bottom end of my OHC is essentially the same, just a deep skirted block (originally designed with cross bolted mains in mind but never happened). My plans are like yours. Forged pistons, cleaned up and checked out stock rods with arp bolts, then boost the piss out of it until I get nervous, can't keep a head gasket in it, or can't keep detonation at bay. If I can keep the tune safe on all cylinders, I'm hoping to see where the next failure point is, rather that is detonation, crank or mains.

I didn't imagine I would have to spin anything over 6k RPM. My motor seems a lot like tom's cam/head/fuel delivery setup on his turbo dyno setup and he didn't make any power past 5500 IIRC.

With everything done, I was hoping for exactly that HP range. 400-600. After that I'd need to redo a lot of stuff for more. Bigger/slower turbo, larger fuel line (6AN to 8AN), probably a better carb setup/maybe TBFI, maybe some type of upgraded ignition.

Yeah I know it's easy to wreck an engine like this in a heartbeat but I meant since I have a good supporting fuel system and detonation shouldn't be a problem because of the J&S system, it should be highly unlikely that those things would be the weak link now. Just wondered where else I'd need to improve for a good long engine life.

I figure with the J&S system, it'll tell me when there's a knock and keep timing in check and then I can always tune with the wideband to keep the A/F rich under boost.

Well dang. what kinda wizardry are they doing to get these 250s to 1000hp+?

Not sure of the cam specs that Tlowe had during the turbo 250 dyno?

But I would think it was not for a turbo application, might have had too much duration & a tight lobe center.
Those two combos are most likely not ideal because it would make the engine not to RPM that high & make good power for a turbo application.

The turbo you currently have will not support 600 HP, might be able to squeeze 375-420 HP range.

IIRC, you said your turbo can support 550 HP,, only w/a small displacement 4 cylinder type engine, not your 250 CI engine.

The guys in Brazil are running 100% straight methanol for fuel & run 30-45 psi of boost pressure.
That is why they can make so much power.
Also, IIRC, those guys also can make 1000 HP on stock cranks stock main caps.

MBHD

Suitcase full of money, a turbo the size of a basketball and a 12 Port head. I think your going to have problems with the kind of boost your going to be running without O-ringing the block and a better head gasket.

Well it said up to 550hp for engines 2.0L-4.0L so it's only a little small. But I do understand I'd need a bigger one for better performance. I'll look into that around the same time as meth injection.

Yeah those 12 ports are great but aren't they like $2000+?

So I just did the math for those Ross pistons from Tom.
Assuming... 3.915 (0.040" over) bore, 3.531 stroke. 2.959cc piston volume (without having to deck the block), 74cc combustion chamber (that's stock right?), .041" gasket thickness, and 0.015 piston to deck clearance (without decking the block)...
I can get an 8.87:1 compression ratio without decking the block. That seems right on the money for a turbo engine.

I don't think I'd need to deck the block. It's pretty low mileage at about 25,000 or 30,000. I've never had a blown head gasket. And that o-ringed gasket I always use works great. Is there any reason you can think of that would I need to deck the block?
Even if I do need to, I was going to polish the combustion chambers too so I can just get a graduated cylinder and measure the cc until I have the desired cc.

Anytime you disassemble an engine the deck becomes warped and distorted and should at least have a cleanup cut done to restore it to being flat and square. Its kinda' like the torque plate thing with distorting the cylinders to simulate the head being on the block when its bored.

As for the head gasket, you have never made a true 15 psi of boost on this engine that it didn't hurt something. Once you get to a point of containing all that cylinder pressure and don't ruin ring lands, you'll find the weak link in the chain real fast.

The guy that had the fastest Opala black Chevy wagon & record holder was using a Siamese 3 port head.
IIRC it ran a 7.8 in the 1/4 mile. @ about 175 MPH
His minimum boost was 30+ & a launch & would go up to 40-45+ psi.

We need to figure out his HP, car weighed around 2400-2600 LBS
Who wants to do the math?

Those Ebay turbos try & advertise more than what they can actually support.
It's just a bit small.
I mean if you had the best set-up I cant see the turbo you currently are using making more than 400 HP to the wheels.

I think closer to 350 HP to the wheels, but I could be off.

The turbo you have are advertising HP @ the crankshaft.

Always good to clean up the deck surface. If you put a true straight edge, it is most likely warped a bit anyways.

Tlowes pistons he sells do not sit flush w/the deck IIRC.

Was wondering if you had ordered a J&S or @ least got your concerns answered?

8.87:1 would be good for your turbo app.

MBHD

It is just a hair over 1000 HP(1050 actually). I figured 2400lbs. with alcohol and supercharged and it came out to 7.76 ET in the quarter mile. Wonder what his turbo specs are? I am looking to get 700-800HP out of mine, and found a couple of turbos in the 1.05 A/R range i'm considering for my 250 build.

Well what's a normal amount to mill off? Because every thousandth pushes that CR closer to 9.5 which is what it would be if it was zero decked

He just answered my questions and gave me a price and told me to talk to him in a few months when I'm ready to buy

You have any links to those higher horsepower turbos?

[quote=CNC-Dude #5585It is just a hair over 1000 HP(1050 actually). I figured 2400lbs. with alcohol and supercharged and it came out to 7.76 ET in the quarter mile. Wonder what his turbo specs are? I am looking to get 700-800HP out of mine, and found a couple of turbos in the 1.05 A/R range i'm considering for my 250 build. [/quote]

I do not think Douglas ever told me his specs on the turbo.
Pretty big though. At least a 80 MM compressor?

MBHD

To clean up the deck at least .002"-.005"

Tlowe could tell you how far down the deck the pistons are,, .010-.020" ? Guessing here.

Ask Tlowe also if there is room to notch the pistons a bit to lower the compression.

As far as turbo,, how much power do you want, do you still want it to boost down low or have the power/boost in in after 3000 RPM?

Forgot, @ what RPM do you see full boost currently? (When the engine was running)
Also, what RPM was it at when first seeing boost?

MBHD

Zero decking is 0.015" down with his pistons. I'll ask. If it's only 3 or 4 thousands then wouldn't polishing the combustion chamber take it down slightly to compensate?

Iirc, it started at 1800 and hit full 15 by 3000. I'm going to play with this turbo setup first but since I'll have all high power supporting components, I might try for 700 plus in the future

I don't imagine I'll be able to make that kind of power AND have boost under 3k

There is no set amount, just totally based on the block condition and amount of abuse it has seen and how much it takes to clean up the deck surface completely. Also, keep in mind that many times your pistons will also need to be cut to adjust each cylinder to get the desired deck height and not just the block. So you can get the deck straight and square, and check your pistons deck height and adjust them for the desired compression you want. Too many people forget or just don't know that decking the block is only just one step of several that is required in achieving the correct deck height for their combo.

You could polish the chamber, or open the chamber up a bit to lower the compression.

Nope, you will not make 700 HP under 3000 RPM. I was just curious on how that turbo I picked out for you actually worked w/your combo.
I am sure glad you did not get a .96 A/R turbine housing.
That would not have been fun waiting, & waiting, did & mention waiting? for the boost to come in.

Forgot to ask, what RPM did your stock engine spin to w/power when running the turbocharger?

Your compression with the pistons having a .015 deck clearance is 9.34, with zero deck it will be 9.62. That is figuring using a 72cc chamber head as a baseline.

I still disagree with the turbo sizing. Maybe the full boost at 3000RPM is what caused the destruction of 2 of his engines. That and wrong fuel/ timing controls. A costly learning mistake for Snowman.

With zero deck and 74CC chamber, I see 9.48 Compression. With a .015 deck 74CC chamber comp is 9.18.

It is worth decking your block to get the better quench. It helps to suppress detonation. I suggest working on the head to open the chamber.
My pistons will/ do have areas that can be machined for lowering the compression.

So then my best bet is to polish the chamber, then take it and get it zero decked it and use the .041" gasket I have to get that .041" quench, and then tell the machine shop to notch my pistons as needed to get my compression to like 8.8:1? Is that something they can measure and do the necessary machine work to get my target? Is it better to take material out of the pistons or combustion chamber to decrease compression ratio?

I also just read up on quench. I guessing the stock quench would be 0.030" (stock deck clearance) + .041" (gasket thickness) = .071" which from what I've read is out of the preferred range of 0.25" to .050". Does that sound about right?

Where are you guys getting the CCs for the chamber size? I can't find it anywhere. Is there an easy way to measure after polishing?

EDIT: I never spun it past 4500rpm because of my fuel system and then after I got the supporting fuel system, I was to scared to because it was already hobbling along. I never spun it past 5k at any time.

You can't run an engine with anything much tighter .032" quench or you will have destructive engine damage. Actually, .040"-.060" is the best range for quench. Also, you are defeating the purpose of trying to get zero deck if you then cut your pistons to achieve something else.

So zero deck with that .041 gasket will work fine.

I've never heard of changing compression by cutting the pistons. I was thinking you'd cut in the center of the piston and make a dish so it wouldn't affect quench.

So they'd have to take it out of the combustion chamber to change the compression ratio? Again what tool would I use to measure that when changing it?

EDIT: I read around a bit more and a few engine builders recommend a quench of .050" for a safe bet. If I deck it down to 0.050" from 0.056" (0.041" gasket + 0.015" deck clearance), I'll get that quench, the deck can be cleaned up with a .006" cut, and I only need to take out 2cc of each chamber for a 9.0:1 CR or 6cc for 8.65:1. Or anywhere in between.

A bunch of head volumes are listed here on our INLINERS website.
http://www.inliners.org/tech/heads/headindex.htm

I understand that. I was talking about cutting material from the center of the piston to reduce CR, I wasn't talking about decking.
So since they'll have to cut all the pistons anyway to set quench after the decking, then it shouldn't be hard to notch them to set the CR right?

Yes, you can cut down the piston where the open part of the chamber is, not on the flat sections where the cyl head deck is closest to the piston, if that makes sense.

Here is my dished piston, it is milled out to follow the shape of my combustion chamber.



Combustion chamber:

First you need to tell us what your target compression is that your going to actually shoot for. Cutting material from the center of your piston isn't necessary if you can get your chamber opened up enough by polishing. By ending up with .015" quench, that is all you need to do to get your compression where it needs to be. I also have heard many top blower engine builders say that quench isn't as important in these engines as it is in a N/A engine. So if you go a little past .060" total, it isn't going to be a tragedy, especially with 15 psi boost.

Ok so let's say I'm shooting for an 8.8:1 compression ratio.

And yes. Hank piston being milled where the chamber opens was exactly what I was talking about. That way it doesn't mess.with quench.


I'm afraid I don't understand what you were trying to say. 0.015" is well under the recommended range you mentioned.

Here is another good read on quench.
https://www.inliners.org/ubbthreads/ubbth...=true#Post69835

No, .015" deck on the quench sides + your gasket thickness will be your piston to head clearance(.040"-.060" recommended).

I missed it, do you have a link or part number to the head gasket you are using?

I don't have a lot of choice and going with the standard Felpro Blue that usually crushes to around 0.041-.042". Hence one of my caviates being, load it with boost until I can't keep a head gasket in it.

Fel-Pro 1025 head gasket
http://www.summitracing.com/parts/fel-1025/overview/make/chevrolet

CNC - Well since the piston to deck clearance is already 0.015" with Tom's pistons, then the highest quench I can have is 0.056" with that 0.041" gasket and the lowest being 0.041" if I zero decked it. So no matter what I do the quench will be in the correct range.

Wouldn't my best course of action be to deck the block as little as possible to clean it up and decrease quench height some. And then just compensate the increase in compression from decking by opening up the combustion chambers to lower it back where I need it?

That is just what he got for deck on the few blocks he has checked, you could have more or less, but you need to physically check it to verify. But yes, if you have .015" deck clearance and only deck the block the minimum and you still have too much compression, you don't have many other choices to reduce it, so cutting a dish in the piston may be an option.

This is a better HG to go with : http://www.ebay.com/itm/051-MLS-High-Per...=item2c82fbb0b2

You can have them in different thicknesses.
These are the best for boosted & high compression engines.
Reusable also.

You need to have your block & head surfaced for the correct Ra number for it to seal correctly.

MBHD