i guess i'd like to kick this forum into gear. this is a call to see who has one, is building one or had one. i want to hear about your engines and experiences. pic's would be a great bonus. i want to hear about it all, little turbos big turbos and even the ones as big as a bucket! superchargers are cool too. i know they are out there. let's get going. tom

Lets start with the turbos everyone is using, mine is a turbonetics T70 compressor with a "S" trim turbine and A/R of .96

tlowe, what is the intake lobe center on your cam your post said it's ground on a 114* lobe seperation is it straight up ?

will post my information on my engine in the next few days

I sit an await these cam porifles
Harry did you think about or try The Lump with the port divider?

ok guy's, i went out in the shop and got the cam card. here are some spec's. lift is .521 int and .512 exh. dur @.050 is 218 int and 212 exh. lsa is 114. valve timing @ .050 is open int -1 btdc, exh 44 bbdc, timing close @ .050 int 39 abdc, exh -12 atdc. these specs are for the cam installed at 110 deg intake center line. i am running it straight up on the cam gear/timing marks. so far i have not reved this engine past 4500 rpm, at that level it is still pulling very strong.

turbo 6, what cam profiles have worked good for you and at what rpm levels?

I run 2 Garret turbos (GTP-38, A/R 1.00 on the compressor side and .68 on the turbine side) on a 515 ci big block Chevrolet. Makes 11 psi boost with waste gates open and 19 psi with them closed. I plan on using the same turbo on the 302 GMC I am now building, it will be EFI using Mega Squirt controller. I also put a GMC 4-71 supercharger on the straight 8 Buick in the #1950 Buick, it makes 8 psi boost, that really helped the performance. Cya

Tom:
Whose cam did you get? What would you suggest for a 250cid? I would like to have a civil engine for mostly street driving/towing. I was going to get one of Edy Rodrigues turbo's but it would cost the same as one on eBay. I need help in getting a turbo that would work well on my engine.

Thanks for your help

Randy S. Hager,

I would stay to about 204 degrees duration @ .050
.440-.480 or so lift,w/a 114-116 lobe center.
Comp Cams are good cams.
They will make what you want.

For a turbo,,, A T3/T4 60-1 Turbonetics w/a Stage five wheel,,,& a .63 turbine housing.
That would be good to about 24 psi tops.
Or a T3/T4 57 trim compressor wheel. .63 turbine housing.

With those turbos on Ebay,you have to watch out for the small turbine housings & turbine wheels.
Most it seems are geared for small 4 cyl stuff.

It really depends on how much boost you want to run?


Two cents

MBHD

Twisted 6 I'm going to try to add lumps to my head, need to get with you!

Tlowe the cam I am currently running is a comp. solid lifter, 244/244 @ .050 int opens 14 btdc ,closes at 50 abdc. exh opens at 58 bbdc, closes at 6 atdc. installed at 108* lobe seperation is 112* lift .605
( old cam 262/258 @ .050 int open 24 btdc close 58 exh open 62 bbdc close 16 atdc 110* l/c .630 lift )
but going to a milder cam more like yours but a solid roller. my cam has too much overlap, and if you have more pressure on the turbine than boost it's bad.

GH- do you have the wheel size of the turbos
comp. inducer (sm) exducer (lg)
turbine inducer (lg) exducer (sm)
the nomenclature for turbos is constantly in the state of flux and don't help much.

I run a Garrett / AiResearch T3 from a Buick Riveria. Not the same as the GN Turbos. Housing siezes are .60/.82 as for the wheels themselves i have yet to measure them but I was told the exh was a Stage 2 wheel.

Turbo-6, I don't know anything about inducers or exducers. I just purchased these because they were cheap, $200.00 each, new turbos for the 7.3 liter ford diesel power stroke trucks. They work great, make lots more power than the 6-71 blowers I ran for years.

GH it's just that the sizes are kind of a way to compare one turbo to another. and the efficiency
(compressor to turbine).

What about caming a 250 for a Paxton Novi1000 reving about 6000-6500? Any suggestion?

I would say something like what I have in my car now.
.580 lift intake & exhaust
Duration @ .050 is 238 intake 246 exhaust.
The lobe center is a 115.
My engine would pull really hard from 3000-7500.
It just wanted to keep revving!

And this was just w/there old race supercharger (SN89)w/the curved impeller & it only gave me 8-10 lbs boost pressure max.
This blower is the gearless planetary ball drive type that slips @ high boost pressures.
It would have been a lot faster if I had the Novi blower on it.Gear driven.
My Camaro ran mid 12's @ 3000 ft elevation track @ 112-114 MPH

MBHD

MBHD

Thanks Hank

I was thinking about a similar numbers for .050 but not so sure about the lobe centre. As the blower fills up the engine quicker than turbo, could it be used with less lobe centre than a turbo cam? Like 112 or even 110.

Do you have bigger exhaust valves?

What about you idle? Is it smooth or rough like a NA engine? I'm asking you that because i'm looking using a blower with an agressive idle. This is one of the reasons why i'm concerned about the lobe centre.

seiscanecos74


Well, with using a centrifugal blower like a Novi, there is some lag also.
So it does not fill the cylinders like a roots/screw type supercharger.

As far as lobe center,,, it idles pretty crazy & this was when I had three DCOE Webbers (which,by the way), makes your engine run really smooth as compared to a single four barrel carb.

With a cam having these specs in a 250 CI engine,even a cam w/a 118 lobe center will idle rough,it is a pretty big cam for running on the streets.

I choose a wide lobe center as to get some kind of desent idle & I wanted it to pull really hard on the top end,which it did.

If you bought a cam with roughly the sam specs w/a 110 lobe center,you will be blowing boost pressure out of your exhaust(causing lower boost)
It will idle really bad plus you will be losing a lot of down low grunt. Your cranking cylinder pressure will be low.

I have bigger valves, 1.88-1.90"IIRC intake & a 1.60" exhaust

MBHD

well... here is my set up!

My engine is a fuel injected Turbocharged 250 Chevy, 6" aluminum rods, 3 stage dry sump oil pump, gear driven mechanical fuel pump, 12 port Sissell´s Aluminum Head with custom JE pistons, 8,5 compression ratio, billet roller Cam (.722 Int and .691 exh cam, 112 lobe center), 2x1500 cfm spearco air-liquid intercooler, 105mm throttle body, MSD crank trigger with Digital 7 Programable ignition with boost retard curve.

Engine is not done yet, because cylinder head just came from USA this weekend. I'm really impressed about the 12 port head and about Mike Kirby´s job.

I´ll start with a Brazilian Turbocharge, the biggest Master Power in production today! .60/1.22 77mm rotor/76mm shaft...
Here is a pic of the turbo!


Now it´s time to make intake and exhaust manifolds to get the engine ready to fire for the first time!!

PS: The guy holding the turbo is not me. Just a guy from the dealer I bought the turbo! I´m a little bit ugly!

Thanks!

Douglas,
that is a big turbo, is that a T6 frame,not a T4, correct?

How much longer till you can fire up your engine approx??

BTW,,,,maybe I could use a turbo exhaust manifold from the same builder where you are getting yours done at.
Instead of him just making a one off set, maybe he can make two?

Maybe from 321 stainless material?
Also need it w/a T4 flange.
Just a thought, let me know what you think.
I am thinking of using 1.625" (or 1 & 5/8th's)
tubing,not sure what size you will be using?

MBHD

douglas, make that 3, mine with a t4 flange. tom