Turbo cams?

How much of a gain over a NA cam. Mid sized BB 9.8comp big flowing -1s.

Way to generalized...

Im using a mp.590 cam in my sb turbo setup. 106lsa. Not optimal,but it works.


I'd say a good cam will new 40-50hp give or take.





Call bullet and see what they recommend.

Was gonna buy a Bullet, got a 660 solid roller Comp I can use just didn't know if a custom grind is worth the extra coin.

What's the lobe separation?

Can't get a very good answer without a lot more detail. How big is the motor, What turbo(s), intercooled? hot side size, power goals, rpm range, what fuel, expected boost, etc?

If you're talking about a low power level on a big turbo with good fuel... Just turn the boost up more and run a cheap cam. If it's a max effort deal then of course it will make a difference.

Single 75mm with A air to air, .030 400 forged bottom end on pump. I have Guppy's old top end, will go up to another 75mm and a 4.250 stroke and a aftermarket block after its bugged out. Wanted to buy cam just once, willing to sacrifice power now as long as it will benifit me later.

card say 108

You need to be wider on the lobe sep. At 108, it is going to blow a lot of the charge out the exhaust on overlap. The overlap is helpful to pull the intake charge into the cylinder on a N/A motor, but you don't need that with boost. Shoot for roughly 114.

Ck

Cam specs are VERY dependent on pressure ratios. A single 75 will choke that engine, and you can follow the "turbo cam" generalizations with that choice.
Point is this... The closer you can get to a 1:1 intake/ exhaust pressure ratio, the more you can let it breathe with a more "n/a" style cam.

That's a very vague statement. the right 76 will be just fine on it. A 76/96 on my 426" sb definitely isn't "choking" they engine by any means.

As straight forward and pointed as I can be. A 400 with worked over indy top end will be choked with a single.

Weird my turbo is rated to 1100-1200hp with a 1.32 exhaust housing and 96mm wheel. will it work, yes. Will it make more power on a larger turbo? I'm sure it will, but what combo wont? Plenty of low 400ci combos with a single 76 makin a$$ loads of power. High 4s and low 5s at 3200-3300lbs. Inlet wheel size is not everything. Without a compressor map for you're just using an incorrect generalization.


If you're class limited to a 76mm inlet wheel there's plenty of power to be made. But by all means go as big as youd want.





To the OP call Jose at forced inductions and he will hook you up with a nice piece.

So what kind of power is your 426 making with that single?

On 9.7lbs it went 137 @3500lbs with 26% converter slip. That's with a NA camshafT, and a baby soft tune up. It's a stock block, 100% street car. It's really going to pick up with the s476 race cover and wheel upgrade.

Why would you upgrade when you say that your single is capable of 1100 hp? You are nowhere near that by your numbers.

it's an easy 40-50 hp at the same boost level, while still being class legal 76mm in a local 8.5 tire class, which is what it's going to shape into late summer/winter.it's just a box stock t6 s475 at the moment, but it will be going to Jose for the race cover at some point Since I'll need It next year Hoping to pick up a r block or ritter block so I can crank the boost up and make it more of a max effort deaL

Still trying to wrap my head around this. Your single 76 has a claimed approx. 400 hp left in it, but you want to upgrade so that you can make 50 more HP than what you do now, because you want to stay at the same boost level? Does your class have some boost limit, or am I not getting it? Things do get by me sometimes!
My point is this. He asked about a cam. What to many people call a "turbo cam" can be good or bad for a turbo engine. An under turbo'ed combo will work fine with that style cam. Put two of those turbos on there, and the cam specs that will work with over turbo'ed engines will have specs way closer to a "N/A" cam with better results.
Trust me, I understand. The power undersized turbos will make on a car feels great... But after you put "proper" sized turbos, You will recognize the "choked" term I use.

It's non i/c at this point, so I'm hoping it's going to help with iat, even tho they aren't out if hand just yet.

The bigger turbo/billet wheel/race cover will move the compressor efficiency up and to the right. That is a good thing when you're running big boost levels and turning a bunch of RPM.

However since you're running at such low boost I would actually expect to see the IAT get slightly worse at 9psi. Why would that pick up 50hp?

What trendz is trying to say is that different turbo's, CID, boost level, heads, etc... Will all want a different cam grind. Some combination of the above will be more like a Na cam, and some will want something more obscure.

Some turbo cams are ground with a reverse split duration, some are not.

Too many factors go into it to generalize anything.

Just talked to Mike at Bullet, Man do I have a headache now, way to much info to take in. Cam he spec for the engine now is nothing like what it needs with 120 more cubes and another turbo, new that was coming, for this engine think I'm just gonna find a shelf cam with enough lobe sep and lift I can live with until I go bigger. Hot rodding ain't like it used to be, but then again thats why we have street cars that bust 170mph In the 1/4 now.

Well gonna run the Comp I have unless someone buys it from me,
It will run what it runs, this is my first v8 turbo, It will run good I'm shur, and when I get another block and rotating assy I can lean on I will buy a "proper" cam.

Thats just a N/A cam.. if I were you I would do
some calling to get a proper cam.. something in
the 114 LSA... you can sell that cam latter

If someone buys it I will order a custom grind, it's new never ran,
It's a month away from being together.

Before you get started on this project and disapoint yourself...

The link below is a borg warner 75mm compressor map at only 10psi of boost on a 500" motor (assuming a 4.25" crank and 4.34 bore). As you can see you are off the entire page (let alone the chart!) by 5000 RPM.

A cam that is 283@.050" is going to want to spin fairly high RPM, which will be a terrible match with this turbo.

To make a 75mm work on a motor this small, you'll only be able to turn it to around 5000 RPM, which would literally mean stock cam.

If you want to turn it to a lot of RPM, then you need a much bigger turbo.

Just don't want to see you spend a lot of time and effort putting a bunch of mismatched parts together...

http://www.turbos.bwauto.com//aftermarke...rsin=92044&

I like that comparison chart you put up
Doug.. I had to save it

I'm assuming the cam profile would change the volumetric efficiency characteristics at different rpm. But aside from guessing about that - I don't understand how the app comes up with info about wastegate sizing. I played with turbine expansion ratios - but it still says I'm wastegate choking?

100% volumetric efficiency is never going to happen with a motor designed in the 50's.

I have Indy heads and a turbo cam and my V/E numbers are in the 80's at 30 psi acording to my FAST fuel tables.

What would be a reasonable "guess" about VE numbers be? 70's?

Look at some dyno sheet... A 440-1 indy head on a 500“ motor will make 100% no problem. My home ported iron heads went around 95% VE.

Especially at low boost

I didn't do anything on the turbine calculations because I was just pointing out the compressor mismatch. You can use this tool for wastegate and turbine calcs tootoo.

A 75mm on a 500“ motor not work well.

It's just a .030 400 right now, I will by another of the same size turbo after I get it all together save for the hot side.

Ah I was confused because you mentioned the 4.25 crank. It will work just fine on a 400".

That cam is still way to big, but at least you're not mismatched on the turbo so bad.

Probably only needs a cam in the 240/250 range. 280+ is going to want to run higher than the turbo can support on a 400" motor.

Yeah Bullet spect one I think at 254, might throw a big Hyd flat tappet In it for now,

this is my cam from scott brown hyd roller ground for 1.6 rockers
adv dur int 293 exh 303 at .050int 239 exh 248 valve lift int .548 exh .610
lobe sep int 110 exh 118 lobe sep 114 spring press 175 reat 425 open
this is a 8.32 comp 440 motor all aftermarket block heads rods crank everything to stock size 440 but made to take the beating of big boost i hope. i was very happy it dynode 510 hp with a 750 carb last weekend when i picked motor up.

What turbo/turbos are you going with?

well we have talked to precision-works turbo and a few more to get a size and basically they all wanted cubic inch and compression and your goal for hp with my combo of 440 and 8.3 comp 88 ml is perfect anything smaller your wasting your time and money but at 88 mm 1000 hp at crank is about max depends on wich turbo you buy. i have a line on a nice precision 94 mm so i can make more wich is funny my whole goal is 9 sec car pump gas but this thing has gone out of control on the budget side way the hell over. my advice call scott brown at buyracingparts.com he will mahe you a great cam my setup was about 900.00 cam lifters and springs

That 88mm will make way more than a 1000 at the crank,
There is one on youtube basically same build, stock stroke 440 eddy heads but with stock block made over 1200 at 16psi on pump gas.

"my whole goal is 9 sec car pump gas.."

I hate to say this, but if that was your goal and you are "out of control on the budget side way the hell over" then you either underestimated big time or didn't plan it out to thoroughly. You should accidentally run in the 9's with a 440 and 88mm.

this dart was going to be a 440 with nos on stock block - no paint well a buddy with a 5.0 stang bought a 120,000 mile 5.0 for 500.00 a turbo kit for 1200.00 put this junk together and went 10.20 so my plan changed and let me say 5 years ago i could not find anyone running 440 with one turbo so this car has been changing. 2 years ago i decided to go and build the most durable street turbo motor that was 440 cubic inches world 4.25 bore block 4340 8 bolt mp crank manley pro I beam rods icon off the shelf pistons ( engine builders choice ) hyd roller cam by scott brown - T&D 1.6 rockers had a s480 turbo i was told it will run out of steam quick so now after getting better info and seeing the you tube motor dyno i think we are getting close. as far as time slips i believe when i see it. alot of people like yourself say im under estimating what the car will run and im fine with that. until i get this pig done i want to have my mind blown i know my wallet is.
buhahahahahahahahahaha still learning about turbos

more

Based on your pics, it looks like you have nice stuff, so I am sure the turbo set up will be equal. With that being said, you should easily run 9.3's.

buddy if I'm in a true 9 sec street car on 91 oct pump gas i will be happy as hell

If that car weighs < 3350 lbs (what my truck weighs) and I run 9.9's on pump gas with 389 inches and a 76mm turbo on only 13 lbs of boost and other such as Diz does the same with a similar set up (I think T6 turbo on 15 lbs but 300 lbs more) then you don't have anything to worry about.

Traction and boost management will be your issue, not power. I have since installed a Hyperkontrol boost management system but have yet to run it.

i have been reading up on hyperactive and talked with the guy I'm getting my turbo from and he loves that system.

It's pricey but it is the best. I like the ability to control boost by MPH rather than time based, in case you are on a marginal track and start to spin.

i agree i hope after you play with it and figure it out that you post your adventure with it i really want to hear the pros and cons of the system.
p.s send me a message when you play with that bad boy!