Inliners International Forums General Discussion Blown and Injected stock engine w/ supercharger??

Thoughts....

Will a mostly stock 250 hold up to being supercharged with 5.5psi boost? Only intend on reving this thing to about 5,000 MAX!

Is the engine going to be freshly rebuilt and machined, or an engine with thousands and thousands of miles on it with a supercharger bolted on it. If its the latter, then it probably wont last long.

The supercharger also adds alot of heat to the air. This makes detonation more prevalent. Agrre with CNC, if the engine is fresh 5 psi will be pushing it. One good fit of detonation and it is all over. Tom

It will most likely hold up,,,,if,,,, you use methanol injection & a safegaurd.

We have crap 91 octane in Cali,My Syclone goes up to 25 PSI w/a simple Aquamist 1S system a J&S safegaurd.

All stock engine w/cast pistons.

http://www.alcohol-injection.com/universal-stage-1-8.html

http://www.jandssafeguard.com/


MBHD

This engine will be 'freshened' with rings, bearings, gaskets, maybe pistons (if the price is right for forged), stock cam, stock head (until I have the one built with larger valves and screw in 7/16" studs, lumps and fully ported.) A 292 exhaust manifold (price?) and a custom intake.

I am not sure whether to use the stock balancer... It is hard to cough up $300-400 for a GOOD balancer (ie; fluidamper or TCI rattler).

Also, do I have the rotating assy balanced?

My big thought was just a 'fresh' engine... no real upgrades to speak of.

Keep in mind that a supercharged engine has increased load applied to it at all times, unlike nitrous that you turn on and off. So just prep your engine with that in mind, and maybe as an added measure, have the block o-ringed and maybe add some ARP bolts rod bolts.

The stock type cast pistons have thin ring lands and are not designed for this.
A forged piston in standard form is also not designed for this forced induction setup. Only a custom order forced induction piston design is going to be proper.

Hank, the piston's in the Syclone, are they a forced induction design with a big top ring land?


292's have a big top ring land from the factory and are a piston that will take the abuse. Tom

The stock Syclones piston are nothing special.
The ring land is standard thickness.

They blow apart like any stock type piston when they get detonation.

If you can control the engine from detonation, (that's why I recommended a methanol injection),it would be OK to use a stock piston. w/low boost as this guy mentioned.

Guys w/stock LS1's have notoriously weak pistons,they get greedy & try to run 9-10 + boost pressure & over 10.1 compression,get a little detonation & kaboom,pistons get wipped out.

They come with knock detectors also,stock.


MBHD

If you have to order a piston, specify for boost and they'll give you what they normally do: lower the position of the top ring land (1/8"? more?) closer to the pin, and increase the dome thickness.

I was thinking of using the ARP rod bolts. Main bolts, too if the budget allows. As for o-ringing... I read that if I use a certain gasket with head studs, there is virtually no need for the o-rings. Keep in mind, I am only going to start with 5.5psi boost. I do have the pulley to go to 10psi and would like to run it, but I know I have to build the engine to handle that.

For 5,000 RPM? Why?

I don't want to over-rev the sum-bit#@ and blow things apart.

I am not sure what RPM the stockish engin can handle safely, so it is better to err on the side of caution.

Tom, wouldn't it take a whole heap of work to make the 292 pistons work for the supercharger application? By that I mean, the compression height is .370" higher on the 292 pistons than on the 250 ones (if my math is right). How could I counter that and not reduce the piston durability?

You couldn't make the 292 piston work in a 250 engine at all. The compression height is too far apart on either to make it work. Also, like Tom said, any standard off the shelf replacement forged piston for a 250 isn't going to have the ring package placed on the piston to be suitable for turbo use. The pistons for his 250 dyno testing were made for the turbo as the end goal, and were moved down the piston to accomodate that useage. You could probably use a Loc-wire style head gasket and be fine without o-ringing, but with only 4 head bolts per cylinder, its a fine line between safe and not....

I have TRW forged 307 SBC flat top pistons w/4 valves reliefs.

I have run a lot of nitrous through my engine + used a Paxton supercharger running 9-10 psi boost pressure for years all on this same engine w/same pistons.

These pistons are not special "turbo" pistons,they are just forged pistons.

You do not need to have a special "turbo or blower piston" in your engine to use a turbo or super charger.

Having the top ring land lower in the bore is a better idea for a turbo or nitrous or blower,,but not absolutly necessary.

If you can control the engine from detonating,a standard will work pretty good up to a point.

Having the top ring land down the bore is less suceptable to detonating self destruction of the pistons,but if the engine detonates so bad,it too will fail,just not as easily.

I used the standard Felpro head gasket w/stainless wire ring,,4.125" bore IIRC. Never blew one of those out.

Also as a note,I did all this Nitrous & Paxton supercharging business before I had any methanol injection or a knock sensor.

I just keeped the timing light, meaning low total timing.
But was all done w/pump gas 92 then 91 octane.

It sounds like this guy wants to play around w/supercharging w/low boost on a stock engine until he builds a more specific engine designed for superchargring.
At least that's my take on this.


MBHD

You are absolutly right, Hank. I want to use a stock engine until I have the money to build it right!

I kinda figured that.

If you want to run a blower,why not,just use the best pump gas available & @ the very least use a methanol injection kit as I mentioned,,if you want it to last @ least for a little while.


MBHD

The stock camshaft should be replaced also to improve engine breathing.

MBHD

What I have been reading tells me it is ok to use the stock cam... or to have one ground to nearly stock specs. I think it even says that in the inline power manual under the supergharging section. I am still going to replace it though.

With the 307 pistons... Would the stock cast units be more durable than the stock cast 250 pistons? I do not have $700 for a set of forged pistons, but if the cast ones simply will not do I am not going to do the build until I have the money to do everything at once!

Dodgy,
The stock lower end will take 5 PSI. There will be a limit and you may find it (hope not). Rpm and detonation are not your friend. If the engine knocks under boost, expect to see pieces come out the tail pipe. Tom

A stock cam is OK to used for a turbo low performance set-up.
For a supercharger,,they do not breath very well.
On my Moms 1973 completely stock 250 Nova. It would change gear @ 4800 RPM. Factory setting for the PG it had.

As far as a blower having a load on the engine @ all times,the factorys have been using a vacuum opperated valve for years that reduces pressure to the engine & less load on the engine.
Whipple has them also as others do.
Ford SC Thunderbird factory V-6 had them. For an example.

Nitrous is much worse as far as shock load to an engine,very easy to break parts.. And more likely blow head gaskets.

As I stated earlier,use a methanol injection set-up!
I also recommend a knock senor install,this will save your engine.
Read up on them when you get a chance.
http://www.alcohol-injection.com/water-injection-kits-1/
http://www.jandssafeguard.com/

I will state again,,,I see normally 21-23 PSI on my Stock longblock Syclone, stock compressor housing I machined for a larger compressor wheel. Looks "stock" right?

cast brittle hyperutectic (SP) pistons that will self destruct in seconds, as do the factory LS1's.

With methanol & a knock sensor installed to pull out timing when detonation occurs,those 2 items alone are worth the price to save your engine.
My friend is a distributer for J&S & he can set you up w/what you need if interested,plus you can use it on other cars if you decide to. http://www.american-pi.com/corvair/corvhome.html

If I did not think these products work I would not say a thing about them. I have first hand experience with both items,I just use a non progressive Aquamist 1S system. http://www.aquamist.co.uk/cp/sys1/sys1a.html

As long as you can prevent detonation,it will work period,as far as you wanting to turn to 5000 RPM,the stock camshaft most likely will not agree w/that. ;-)

Also,again,just because a person would read a supercharger or turbocharger book stating the piston should have a thick crown .250" minimum top ring down the bore,does not mean you absolutly need to.

As I stated before & I guess I need to again,I have standard 307 TRW forged pistons in my engine,the top ring land is in the standard ring package,(not .250") down from the top of the piston).
I have used anything from a NOS nitrous "cheater" kit minimum 150 -175 HP jets,, minimum engine size 350 CI (for the use of this Cheater set-up)
I will tell you ,it rattled/detonated soooo-bad I thought the pistons would have blown up in seconds,,,but they did not.
B.T.W.,my car never felt so fast,,,,& it was detonating like mad @ the time I used the NOS,my front end of my car raised about four inches higher & it was hitting the top out "A" arms snubbers & the steering was really light!

After Nitrous,I used a 194 cylinder head milled it,ran 12:1 compression,after that, I fabbed & installed a Paxton supercharger set-up blowing through 3 48 MM DCOE Webbers.


Hope this helps any ,I have 1st hand experience in different engine combos,cams,blower,nitrous etc.
I do not claim to know it all,but I have done a lot w/my 6 cylinder.

BTW,the 307 forged pistons & original shortblock are still together still in my car & never fresheded it up.

For my next venture,I will install my SPA turbo manifold,Turbonetics T3-T/4 hybrid 62-1 turbo EFI,onto the same shortblock that has been in my car for yeeeeears,just to get used to the EFI stuff & tunning,then I will build a nice designed longblock engine specifically for a bigger turbochager.

Thanks for your bandwidth.

All these differnt things I did to my engine all took place in a couple weeks time,,,,,,,,,,,,,,,just kidding.

Most all the transitions/work done was when I was single,no kids, & had help from my friend that knows cylinder heads & much more.

MBHD

I have done a lot of reading into the water/ meth injection kits, and I have definitely figured on using one. Though, I have read that I should not trust to this type of detonation suppression since when it runs out of fluid, I am no longer protected. Makes sense... but how fast do they go through the fluid? I do not know this as I have never even seen one in use.

I also looked into the MSD ignition retard box.... retards timing 1-3 degrees for every psi boost. I have posted questions on the turbo forums, but everyone seems to be too good to answer a question like that. Or maybe it is just MY posts that they don't like.

The reason I ask about the cast pistons from the 307 vs the 250 is that I cannot afford at this time to buy a set of forged pistons. So, I wonder if the cast 307's might hold up longer than the cast 250's... I can buy them cheap enough! Again, at this time I am only looking at 6psi MAX boost (at least until I get the forged pistons and the rotating assembly balanced and and and...)

I thought that the 5,000rpm was not asking too much from a stock cam, but I guess it is. I don't have a problem with only 4,200 or maybe a little more? I do NOT want this engine to grenade as it is my ONLY car and I have to drive it everyday!

There are failsafe products so when it does run out of meth or nozzle gets plugged.
Just an example http://www.snowperformance.net/product.php?pk=13
You do not use too much fluid,it does last a while.
If you plan on flooring it everywhere you go & do not want to refill tank a lot. Get a 1 gallon size tank.

I just use my windshield wiper fluid tank.
My full size truck has @ least a gallon size from the factory.

Here is the definative answer as far as using a MSD retard box.
It cannot sense or hear detonation ,so when your engine is detonating while using a boost retard box ,the MSD will only retard timing for what you set it to,so in short,,,it will not retard your engines timing to save it,just retard timing you initially set it to.
The J&S will hear/sense knock & will pull timing out accordingly.
http://www.jandssafeguard.com/

What answers are you getting from other forums?

As far as cast stock 250 or 307 pistons,they will hold up to about the same amount of abuse,which is not too much,especially when super or turbocharging & detonation happens,they will fail very quick w/detonation & forced induction.

I understand about being on a budget,but if you are going to bore an engine ,install new pistons,@ the very least, do yourself a favor,save some $$$ & buy forged pistons & good rings.

Also,if this is your only car & you are insisting on supercharging it,,,,it's manditory to purchase & use a methanol injection system @ the bare low cost MINIMUM!

Some sort of knock sensor set-up that can retard the engines timing like the J&S would be my other bare minimum.

1) Methanol injection system
2) J&S.
Hope you realize how criticle this is to have on your car,it's to save/protect your only driver.

MBHD

Hank,

I do realize the importance of have some type of fail safe... knock sensor, meth injection, BOTH! I understand that need.

On the turbo forums I get people saying that the meth injection should not be relied on because they fail often enough. I have visited all the sites I can find about the kits and they look to be great things! I did plan on using one. Another thing they are telling me is that I CANNOT run the injection PRE-supercharger/ turbo. They say this will cause catastrophic failure of the impellors... but why then do most superchargers have the carbs mounted on top?!

On the Internet everyone is an expert, and if you ask 10 more people, you'll get 10 more opinions.
Pre-impeller liquid is potentially dangerous:
1. in large doses
2. at low pump pressure
In other words, using a 10 psi windshield washer pump with a 3/32" jet is asking for trouble.
A 100 psi pump and a 1/32" jet avoids most of the danger with introducing a fine spray that does not have large droplets smacking the blades and causing local erosion and temperature changes.

Not to step on your foot, but questions like "why then do most superchargers have the carbs mounted on top?" indicate to me that you have a way to go before understanding what's happening will allow you to make your own decisions. Right now, good advice is the best plan.

They're on top because they won't fit anywhere else - sounds silly, but there are no successful SCOT, GMC, Weiand, B&M, etc. manifolds to do this, too big, too heavy, makes the drive much longer.

A simple push-to-test over-ride button to cycle the pump with a green "function on" lamp may make you feel better.
You can put a small Hobbs switch in the pump discharge hose that must "see" pressure or it kills the ignition, opens the bypass valve, opens the BOV, triggers spark retard etc. when boost is on (a critical circuit must get 2 positive signals to work: 1 each from the manifold boost pressure sensor and 1 from the injection discharge). The water switch can be wired into a timer to delay it for 1-2 seconds to prevent premature triggering.

I do understand the way a supercharger works... I was asking a rhetorical question. (I hope that doesn't come off as me being cocky or anything!)

I know that most superchargers are draw through because of their design, space limitations, weight etc. Roots style, anyways.

Sadly, I also know about everyone being an 'expert'! I ask as many questions as I can to as many people as will answer so that I can be better informed before making decisions... I am sure it shows on this topic, but I have NO experience with turbo's or superchargers. That is why all the questions.

The more questions I ask the more expensive the build gets, too. I was hoping to do a cost effictive (not cheap) build, but that doesn't seem to be able to happen... forged pistons, balancers, camshaft, cylinder head, maching work, boost/ timing controllers, injection kits, etc. It is getting to be quite a lot more expensive than I had anticipated. But then, that I why I asked about using a stock engine... to keep the cost down. I know it won't be a rocket ship, I am just looking to do something different!

I may just stick with building the inline to be n/a with one of tlowes combinations. 300HP is pretty darn respectable!

On a roots supercharger the lobes have a large mass and do not turn as fast as the impeller of a turbo so the liquid fuel does not harm them, a compressor impeller is very thin and can not take the mass of fuel as well.

A super charger will spin at 9,000 RPM ( if 50% overdrive at 6,000 RPM engine speed), but a turbo will spin 120,000 RPM at 3,000 RPM which when fuel or water hits them they could be harmed, a draw through does work but at a certain point it does become an issue.

Don't give up on a turbo set up. A new rebuild on a stock 250 with only sealed-power pistons (cheap) will hold up to 400+ HP stock rods, head, cam, block, crank, turbos make lots of torque so you don't need a lot of RPM. Gear it high!

RPM is what kills engines

Harry

Liquid can be introduced on the discharge side - it just requires a stronger pump.
I worked on a (then new - my dentist's car) 1979 Riviera with 3.8 factory turbo and QuadraJet, added a Spearco water/alcohol, ran quite a few years without problems.

X2: RPM means "ruins people's motors".

For the record,the Aquamist 1S system I use on my Syclone does not really add all that much methanol,I mainly rely on it to cool down my intake charge.

There are guys that run so much methanol,they need to take out the fueling tables from there injectors,reduce there spark plug gap.

When there combo has a malfuntion w/methnol injection,that is a recipe for disaster unless they have some sort of failsafe item,like when the alky gets plugged or pump stop working,the wastegate will open & not produce any boost,for example.

MBHD

I did look into turbos. Quite a bit , actually.

I came to the conclusion that it is 6 of one half dozen of the other! Supercharger, turbo, they both require about the same amount of work and money (from what I can tell!). I have never seen a supercharged inline (in person) so I though I'd go that way with it. I am not fussed either way. Supercharged or turbo'd... doesn't really matter to me, because I am looking for the end result. A nice little street thumper!

There are other considerations:
1. the turbo works well with a good iron manifold, but a blower pretty much needs a real header ($$, noisy, only lasts a few years)
2. the underhood heat is much higher with a turbo
3. the underhood noise is higher with a blower
4. you have to figure out your pulleys to get the correct water pump, alternator, PS speeds, and the proper blower drive ratio, you may need a jackshaft. See my article:
http://victorylibrary.com/mopar/blower-drive4.htm
5. boost can be adjusted more cheaply with a blower by changing pulleys, but the load is constant (unless you use a Mercedes etc. electric clutch). A turbo is freewheeling and consuming almost nothing under light throttle
6. turbo boost with automatic is limited in 1st gear unless you have some stall speed, with a blower it can be at 1,000 RPM (although this may wreck the engine).

Dodgycanuck kinda like this its a little dirty been in the car over 10 years but needs to go t
o the hospital



[]

Here is a supercharger intake manifold.
IIRC it was Hunter perfromance that made them initially?
He used to sell them w/a B&M supercharger w/a special longer snout on the blower.
Jules Glauvison?

http://prostores1.carrierzone.com/servle...manifold/Detail
http://www.34-chevy.com/

MBHD