Inliners International Forums General Discussion Blown and Injected snowman4839 turbo build

Yes, there were several tests done between a lump vs. boss-less head, and a tapered boss vs. stock boss head.

Just installing big valves in the head, but not removing the boss gained very little HP, tapering the boss showed no additional gain, removing the boss altogether gained 30+ HP, adding a lump gained more....

So in theory removing the boss and adding a short bolt in place that sits flush with the head surface would be ideal next to installing the lump? Just want clarification.

I think in leos inlinebook he gives good picture examples of both boss removed, lump installed and the boss "narrowed"

Reference pages: 108-119


For those who have the book if not i reccomend it

Hank

The reason I asked was because when I was thread chasing my block,head and crank I noticed one of the valve studs was taller my 1/8th-3/16the taller than the rest

You have to remember.
All the testing (A.F.A.I.K.) having lumps no lumps, larger valves, small valves, boss, no boss,etc, were done on a N/A engine, the results will be different when you have air/fuel being forced into the chambers via turbocharger.

On a N/A engine a good flowing cylinder is crucial to making good power, not as much when forced induction is concerned.

Example, on a N/A engine, if you port too much on a 250 head, making all the ports huge, the air velosity slows down so much, you will loose low end torque & pretty much everywhere else in the RPM range.

If you do the same to a 250 head & slap a blower on top, the engine will make more power as long as you have a big enough supercharger. Bigger ports, bigger windows, allows more air/fuel in. It is more forgiving.

A guy did some porting on some Vortec V-6 heads (for a Syclone), flow tested before & after, the after porting flow test results were worse than what the factory stock head flowed, yet he still installed these ported heads on that flowed worse than stock & his Syclone ran faster,, just saying when forced induction is concerned head flow numbers are not as critical.

Hope that makes sense?

MBHD

Thanks, forgot he covered that. I'll take a look.

Well, theres not much theory to it, its documented and proven to be fact. But yes, just removing the bosses will net you the single biggest increase with a 30 HP minimum gain from what we saw with all the dyno testing done.

I see some clashing going on here tom care to chime in?

They could possibly be pulling out.

MBHD

Turbo6 here devided the intake ports on his 292 to get more even fuel distribution.

Doing so makes the intake ports too small, smaller ports.
To get the same ammout of power as before when the ports were bigger(not devided), he had to increase the turbo pressure, by quite a bit just to make the same ammout of power as before he devided the intake ports.

MBHD

Clashing in what way....

More just both exibiting informational statemets and was curious as to see toms info about the bolt boss remover vs lumps vs slimmed

That info was printed and distributed amoungst the contributors of the projects, but some tidbits were posted here as the testing was taking place. If you search for them, you can find under "292 Dyno Testing", I think. It was right at 3 years ago now, so you might have to dig a little to find the posts.

I think your right Hank, the 250 turbo swap was the last batch of tests done and not a whole lot of head swapping was done for that test like the 292 had done to it. I guess we need to do a series of turbo engine dyno tests now. I have wanted to punish a 292 with a turbo for a while , my race car is ready, I guess its time to start gathering parts. You up for it Tom?

Not today, I'm sick or atleast recovering. Have not ate anything substancial in 2 days. My stomach sounds like there are gerbal races going on.

There is no doubt that adding lumps is the key to adding power to a siamesed port. Anything that can improve performance in N/A will also add power in turbo/ supercharged mode.

Keep in mind when adding lumps. Upsizing the valve is crucial. Stock size valves will not add any power. Minimum size should be a 1.84 valve on the intake.

By cutting out the bolt boss and leaving it that way. Velocity will go down in the port. The motor will become lazy and inefficient at low rpm.

Thanks Tom. Appreciate the help.

will any carb hat work? are some better than others what are those of you who have a turbo build running?:)

From my experience, the picking is slim if you are on a budget. I ran a spectre one but did not care for its 4" inlet. I am now running a very slim vintage Offenhauser carb hat. It probably doesn't flow really well, but looks great.

A good and inexpensive option is to buy a billet aluminum carb storage hat ($15) , cut a hole in the side and then TIG a aluminum tube to it. You could play with different lengths and angles. It would be under $25 if you can fab / TIG a little.

Tig welding is no problem for me i seen a few on ebay but i wasn't sure if the shape or design mattered woth it being forced air into electronic injection(powerjection|||)

Boucher

Also what is a good inlet size would 2" be too small just right

What is the reason behind not liking the 4" inlet loss of air velosity?

Much appreciated, josh

update!! I'm selling a tech toy of mine and that should give me enough to get a piping kit and an intercooler. Should have it and have it on the car in about 3 weeks

Your car will appreciate that upgrade. The transmision may not.

why do you say that?

Like everything else on my engine, it's going to be an ebay intercooler. Is there anything wrong with a large intercooler like this?

http://www.ebay.com/itm/UNIVERSAL-25-x11...cf8136a&vxp=mtr

The intercooler will lower the intake temps. If you keep the same boost pressure at intake, the engine will produce 10-20% more power. Or torque in your case. The clutch and trans will start getting stressed!
You will also be able to run more boost (possibly).

I see no problem with that intercooler.

That intercooler is a Tube & Fin Design, they are lighter weight, cost less but can get damaged easier than a bar & plate design..

More here: http://www.ehow.com/facts_7707839_bar-vs-tube-fin-coolers.html

MBHD

Do well do you guys have any preference one way or the other for bar & plate vs tube & fin? I can get either in similar size for about the same price. I seem to be leaning toward bar & plate because they're less susceptible to road debris (longer life) and they are denser in material which would lead to more heat absorption.

I personally have s bar and plate type

Bar & plate here.

MBHD

I also have bar and plate. Any intercooler is better than none. Yours should be installed in a somewhat protected area. No rocks to hit it.

Just got the intercooler installed. Turned the boost back up to 15psi and tuned the carb to it so it stays nice and rich. Runs like a top but is ruining the block. The rings are taking a beating and blowby is becoming a lot more apparent. The oil still looks pretty clean though so I don't think I've broken anything. I'm saving up to finish rebuilding that other block and I found a set of apparently forged pistons for my 250. They're from the later era with the integral head and it has "0.015 higher compression distance but I don't know if that would be enough for it to hit the head when it's all bolted on. It seems like it wouldn't be a problem with that thickish fel-pro gasket with the metal rings built in and it would just raise the compression some.

Is this something that would work in the older style blocks without much (or any) modification?
http://www.ebay.com/itm/CHEVY-250-FORGED...1428cff&vxp=mtr

here are some pictures
BEFORE


AFTER

Your blocks probably fine, its your pistons that have given up again, the ring land is probably already lifted and no longer is supporting the rings like they should be.

will it beat your old man's Buick yet?

Those pistons will work, they are lower than stock compression pistons I used them & they did not blow apart.
I do not like that the top ring land is exposed as compared to your stock piston, but it is forged & they are a lot stronger than your stock pistons.
Congrats on the intercooler install. But,,,,, I do not understand why you decided to go back to 15 psi on pump gas & not having any boost/timing retard devise,or have a methanol injection of some sort.

Your pistons are most likely shot, rings lands broken & broken rings.

Questions, after adding the intercooler & all that piping, did you notice any more turbo lag, takes longer getting into boost?

Does the engine run any hotter having that big intercooler in front of the engines radiator?

What is the actual intercooler you bought? Specs, bar & plate correct?

Updates? Is it still running?

MBHD

T.T.T.

Any updates or answers to hank?

T.T.T.

MBHD

Bump, TTT
http://netforbeginners.about.com/od/b/f/What-Is-Bump.htm

MBHD

Snowman,

Achmmmm.
Updates? Engines a goner?


MBHD

Snowman,
I see you are from Memphis so I would suggest you search the local circle track suppliers in your area for methanol; very popular fuel in the modifieds and late models. Buy it in 5 gallon quantities for your use and keep it tightly sealed as it attracts moisture when open to the atmosphere.....fats