Inliners International Forums General Discussion Hi Performance Lookjing for 300 Hp What can I do?

The 292 piston is kinda' a one of a kind, and doesn't share any commonality to any SBC pistons other than the bore size. The wrist pin location is what hurts the 292 for any swapping. If you are looking for something for turbo use, then you will need to stay with a dished configuration to keep the compression tolerable. Unfortunately, the cost of custom forged dish pistons is the same for dome pistons, and pretty expensive. But consider it an upgrade and something you will hopefully only have to do once.

I have head that 250cid l6 you can use sbc 327 pistons. Is it true and what kind of compression it will give? Is 250cib better motor if we are looking for turbo set up?

For a 250 engine, the 307 Chevy pistons interchange with these engines. The 327 can work, but you have to bore the engine out to 4" to use these, and that is getting the cylinders pretty thin. The compression will depend on whether you use a dish, flat top or dome piston. Good results can be had by turbocharging either the 250 or 292.

My pistons with pins were 680 from Venolia but they were pretty specialized.

Ok, thanks guys, you´r helping me a lot. If I decide to order forged pistons is it better use flat top or dish pistons if I´m going to turbocharge 6-8 psi, under 10 definitely. What kind of compression I get by using flat top piston and stock heads (with bigger valves 1.94/1.60 and lump port kit.) SBC valves are similar, am I right? How well stock camshaft will work in turbo use?

Tzei,
The 292 piston is a very tough designed piston in stock form. It is designed to withstand heavy loads and detonation(to a degree). There is a steel plate installed under the top ring and across the piston top. On a 292, I would not be afraid to boost 5-6 psi and if intercooled and great timing control 10 psi.
Compression at stock level is good (30 CC dish) , if going to a new piston 9.0 CR is good to aim for.

A stock cam will work well with stock compression. Tom

Just a F.Y.I., detonation normally aspirated is different when using a forced induction application.

Forced induction detonation is much more severe.

With the advancement of electronics,knock detection devices,methanol injection you could run more boost w/cast pistons.
My Syclone has stock weak cast pistons & I have run up to 25 psi of boost.

Others have run as much as 27 PSi on stock cast pistons.
It all depends on how much you want to spend to protect your engine from detonation.
MBHD

So what type of pistons should be used with a turbocharged engine? And what turbo will provide low to moderate boost? on this engine I'm looking for ten lbs maybe a little higher.

I think there is no absolut thruth using pistons but I think that I try to use stock pistons ...or not... I have to think about it... But this information is very helpful, thanks guys!

But how about turbo? Can you recommend some specific turbo, if I´m trying to stay below 10 psi and seeking as much power and torgue as possible at low rpm? And I´m going to use carburetor, so please give me some advise what kind of blow thru carburetor you can recommend. Yes, yes I know... EFI is much more better, but still...

Tzei from Finland

Let us know what size engine,manual or auto trans, etc.

If you are going for a low cost set-up.
A Holley carb will do. A 2 bbl is fine,500 CFM preferred.

Let us know about your engine,vehicle etc.

MBHD

I have just did a turbo 250 for demonstration purposes. It ran 5 psi thru a 500 holley 2 bbl and worked great. My first choice for a carb would have been a 390 4 bbl in a double pumper, not with vacum secondaries. Don't have one of those. So the 500 2 bbl sufficed.

For the 292 you have, as a reference, I run a turbonetics 62-1 T04 with a .84 exh housing and a P trim wheel. It can provide plenty of air.
Another good choice is a 60-1 with simular exh wheel and housing. I also think a .96 housing would be a better choice to help keep the turbo from spooling too fast. The housing and wheel are kind of like tuning aids for boost. Another thing, if you get a smaller exh houising (.68) , the turbo may become a exh restriction. It is a good idea to install a pressure port in the exh manifold to check the pressure under boost. You really do not want exh pressure to get to more than 2 time intake boost. That is a sign that the exh wheel and housing are too small and restricting you motor. Tom

He wants power/low end torque.,Only 10 psi max boost.

A .96 housing would be a horible/incorrect choice. Too big period.

An improperly designed wastgate plumbing will not control boost as Tlowe has.

If the wastegate is properly sized,plumbing,correctly designed,wastegate controller working correctly,as I have stated to Tlowe before,,a .68 turbine housing would have been no problem for Tlowes 292 to control the boost.

MBHD

Alternative to all the mod's is to swap in an '06 up 4200 - 291HP in full emissions trim - bet 310 HP with a good flowing exhaust.

I agree,much more modern designed engine,is always a good choice.

It's all about the headflow,4 valves per cyl,& two overhead camshafts don't hurt either.

My set up right now: Chevy 1948 Fleetline with l6 292, th200r4 and 3.00 rear end gear ratio. Planning to update bigger valves 1.94/1.60 and lump port kit. If I decide to use stock pistons CR will be 8:1, but if I use forged pistons I think I´ll use flat top pistons and I think CR will be 9:1. MSD6462 and HEI also on my list. Low cost is not my main target mut lets keap costs reasonable.

Is holley 2bbl 500cfm ready to blow thru or do I need to make some modifigations or use pressure box? Some guys recommended me to use dellorto DHLA 40 or DHLA45 carb. God this is really hard to find perfet combination...

And NO, I do NOT want to swap any new style motor...

The 500 2 bbl will need very little done to it. The power valve channel restrictions(PVCR) are very big and can flow alot of fuel as is. Make sure any carb you use has a black Nitrophil float, it will not crush under boost.
If using the 390 4 bbl double pumper the PVCR channels will need opened up to allow more fuel flow. They are small as the carb comes out of box. This would be a better streetable/ responding carb.
Either one of these carbs will limit your hp though. Probably to around 350 hp or 5200 RPM because of restricting air flow. If that is all the rpm you seek then they are good. If you want more than a 600-650 Holley double pumper is for you. Same basic mods need to be done to the 650 size carb, PVCR upsize as needed, block choke rod, nitrophil floats, jetting. Tom

So you really don´t have to do anything else new out of box holley 500 2bbl carb for turbo use than make sure there is nitrophil float. Am I understand right? 350hp is really enough, at leas for now... As I said earlier 250-300 is main target, daily use, reasonable fuel economy, etc.

If I use flat top pistons and original 292 head is CR somewhere close 9:1?

And one thing... I have seen some brasilian website selling turbo exhaus manifold (and whole turbo kit for chevy opala) but I cannot find similar from US.Any help?

The 390 4 bbl will deliver better fuel economy, it allows more tunability. tom

I am pretty sure if you custom order flat top pistons & is close to the top of the bore,the compression ratio will be really high.

To my searches,there are no turbocharger kits readily available,ready to bolt on & go for our inlines.

The problem w/using four or 2 barrel carbs,is the the throttle shafts will leak under boost,more so w/running a used carb,throttle shaft/s most likely worn.

Part of the reason I ran Weber DCOE's was that the throttle safts are sealed & do not leak,@ least the ones I had were ball bearing throttle shafts also.
They did however leak in other areas that are not supposed to leak,,not bad,but they did.

If you can use an inclosed carb bonnet cheap,that might be a better way to go,a complete incloser.

But, you can use a standard carb bonnet.

Companies make carbs made for blow through 4 bbls,but will cost you $$$.

MBHD

How about this one?

turbo kit

or did you mean not available in the US?

I think he's referring to a more complete kit that requires fewer additional parts and less fabrication, with an exhaust system that connects directly to the existing pipe, linkage compatible with the original, etc.
That would be specific to an individual chassis (truck vs. Nova vs. rod vs. Impala), and more expensive.

An advantage to buying a blow-through car is that it comes pretty well jetted (well, as close as you can give the specs), and they talk you through minor adjustments after it's running.
There is some good info on modding carbs for blow through on many BBS, including:
http://web.archive.org/web/20070810125306/http://www.vs57.com/carb.htm

I have some comments on my page here:
http://victorylibrary.com/mopar/blower-carb6.htm

[quote=Tzei
If I use flat top pistons and original 292 head is CR somewhere close 9:1?

[/quote]

A 292 with flat top pistons will have almost 11-1/2:1 compression.

Yes I meant in the US.
That kit is just the basic parts needed to get started.

Typically a complete bolt on kit would cost about $4500,this is a rough estimate. But this would be a complete kit w/nothing else needed. US dollars.

The kit from the link would be OK to purchase,it's just the import taxes & shipping thats hurts to buy a set-up from Brazil.
1.980 R$ ,dont have a conversion chart handy.

MBHD

I would also look at the Rotrex supercharger from Denmark. Basically a turbine compressor that is shaft driven with a traction drive system. The traction drive results in better performance than a standard centrifical supercharger. Jackson Racing in the states is selling Rotrex supercharger kits. Jackson Racing has a good name for Miata and Honda engine performance products. The Rotrex has been developed beyond the initial stage.

http://hotrod.automotive.com/81380/hrdp-0512-rotrex-supercharger/index.html
http://www.rotrex.com/Home.aspx
http://www.jacksonracing.com/
http://www.modified.com/tech/modp-0905-rotrex-traction-drive/index.html

Let´s talk about plan-B. It seems that I can reach my power target also without turbo. The turbo is stil first option becouse it is kind of fun put turbo engine to -48 model car. But, I also have plan-B: Lump port head with 1.94/1.60 valves, flat top pistons zero deck (Santucci book says that using 292 head CR will be 10.5:1), clifford intake with holley 600cfm 4 bbl vacuum and some fine exhaus manifold. BUT, how about camshaft? Street car, everyday use, torgue at low rpm and fuel consumption is important, and lots of power ofcource There is good information table concerning 250cid but any suggestion this kind of 292 set up?

torgue at low rpm and fuel consumption is important, and lots of power ofcource

Pick one, not both.

Basically, you are not going to have a very stretable,w/gas mileage combo w/the HP you are looking for.

The type of cam needed to make that power,can be streetable,but mileage will not be very good.

Using a Turbo should cover what you are looking for & still get OK mileage.

You will not make anywhere near the torque a turbo can give you.

With a turbo,it will make the power sooner & make it easier on your engine,as to a normally aspirated engine,you are going to have to rev it pretty high to make 300 HP.

Here is a super cheap $$$ I had given input on parts to use.
http://www.youtube.com/watch?v=xSB2uvlOOtQ
He probably spent $400 tops I think it was less.

You can buy a used stock turbo for a Buick GN or T-Type,or even a used Syclone or Typhoon turbo.
Typically a good used Syclone or Typhoon turbo will sell for 200-300 range.
Another option is buying a new import turbo off of Ebay,just an example http://cgi.ebay.com/ebaymotors/New-T3-T4...sQ5fAccessories

You can buy a used good turbo,100-250 range,fab up a "J" pipe from the stock exhaust manifold from weld El's from Mcmaster carr
Like schedule 40 tubing.
A plain jane Holley fuel regulator http://www.amazon.com/Holley-12-804-Fuel-Pressure-Regulator/dp/B00029JC6M & use a Holley 2 or 4 barrel carb.
If you want to run an intercooler, buy a universal intercooling pipe kit from Ebay just an example http://cgi.ebay.com/ebaymotors/CXRacing-...sQ5fAccessories

Buy one of these for a down pipe http://cgi.ebay.com/ebaymotors/3-45-180-...Q5fAccessories.

If you shop around & take a few tips from us here you can have a super low buck blow through turbo set-up on the cheap!


MBHD

My engine is a stock Chevy 250 from a 72 chevelle.It's got a powerglide and 307 gears in the back. Weighs 2900lbs. I have an offenhauser intake witha quadrajet on it....is the quadrajet to big for it? will it need rejetting? It has some running problems. cuts out under light throttle but runs okay when at WOT. I thought it was running to rich before and I couldn't even keep it running. But now I can drive it with thi new accerleation problem still too lean?but I know in the 80's the q-jets came on the 4.1 liter 6's in regals.

I know in the 80's the q-jets came on the 4.1 liter 6's in regals

????????

Is the accelerator pump working/ good?

What car is the QJ from?
What did you do to re-jet it?
What primary main jets?
What primary metering rods?
What secondary rods?
How much air valve tension?

Well. I don't know what it came from I just swapped mine with one of my cousins. I didn't do anything to it. Just bolted it on to see if it would work. And it did, now I am wondering what to do to make it work better.

Try & find the jetting specs on the Pontiac sprint 6 cyl engine Quadrajet ,,metering rods etc. Should be pretty close to start with.

Quadrajets carbs can work pretty good if you know someone that can work some magic.
Or buy a book on how to tune a quadrajet carb.
http://www.amazon.com/Rebuild-Modify-Rochester-Quadrajet-Carburetors/dp/1932494189

http://www.amazon.com/Rochester-Carburetors-Doug-Roe/dp/0895863014/ref=pd_bxgy_b_img_b

What kind of vehicle you have that weighs 2900 lbs? Early Nova?
MBHD

The original Sprint carbs are listed here:
http://highperformancepontiac.automotive...etor-chart.html

Here is some good info also.
http://www.mre-books.com/quadrajet/index.html

MBHD

The pistons in my 292 were made by J E and cost $680 with pins, clips and rings.The pin height in the 292 makes them a rare bird.