Turbo and cam options

[MeanGreen&Fireball]

Okay, I’m completely new to the world of forced induction. I’m reading as much as possible but a lot of this is just estimating what might get me in the ballpark of a fun ride. I’m asking for help and guidance from the group that knows more than I do. Will this turbo work well on the 200 and which cam would be the best option?

I’m running a 200cid, with mostly stock components. I have a 78 large log head, non-ported with stock valves and stock springs. I know I’ll probably have to change out springs to accommodate the new cam. I’m not looking for the 200 to make all its power on the top end since I doubt I’ll be in that RPM rang much.
I'm having a exhaust manifold built to accommodate the turbo. I’m having an issue choosing the cam and turbo set up. This is what I found so far. This is not the ultimate build for me, this is just an intro and learning experience to forced induction for me. I found two cams but which one is best? I would like the cam to have just a tad bit of lope for fun and a turbo that Will spool pretty quickly. I want to run 8-10 lbs of boost…. Nothing crazy.

 

[pmuller9]

If you are looking for good turbo response the overlap on the cam profile should be minimized.
If you are using a log style exhaust manifold the exhaust duration can be less than the intake duration since there will be no exhaust scavenging.

An exhaust manifold with primary tubes for cylinders 1,2,3 going into one collector and tubes for 4,5,6 going into another collector, then joining the two collector outlets into a "Y" pipe will give the best results.
In that case the cam can have a single lobe profile where the intake duration is the same as the exhaust duration.
I would be looking at the Schneider 131H if you're not looking for power over 5000 rpm and want to focus on the low rpm end of the power band.

The 52mm turbo you posted will work for power between 2000 and 5500 rpm.

What did you want for a power band?

 

[MeanGreen&Fireball]

If you are looking for good turbo response the overlap on the cam profile should be minimized.
If you are using a log style exhaust manifold the exhaust duration can be less than the intake duration since there will be no exhaust scavenging.
A manifold with some primary tube length going into a collector and also separating cylinders 1,2,3 from 4,5,6 before going to a "Y" pipe will give the best results.
In that case the cam can have a single lobe profile where the intake duration is the same as the exhaust duration.
I would be looking at the Schneider 131H if you're not looking for power over 5000 rpm and want to focus on the low rpm end of the power band.

The 52mm turbo you posted will work for power between 2000 and 5500 rpm.

What did you want for a power band?

Thank you pmuller9,
I’ll be running a log style exhaust manifold. I’ll be sure to look into the Schneider 131 H, even as a kid I always had a tendency to chose too large of a cam for my application as I circled parts in the magazines . Is there any other cam manufacture that has a cam more suited for my application? I was looking at a power band somewhere around 2,000 to 5,500.
Awsome, I was afraid that turbo would be too big or not suited for the flow of the head but if it has a power band of 2000 to 5500 rpm that leaves me plenty of room. Truthfully, I don’t know if I will ever hit 5500 or 6000 rpm confidentiality without waiting for something to come apart.
again thank you for the advice.

 

[pmuller9]

Is there any other cam manufacture that has a cam more suited for my application? I was looking at a power band somewhere around 2,000 to 5,500.

Schneider will grind you any profile you need.
If you want to push to 5500 then have them make a profile with the .050" duration closer to 214 degrees on the intake and a few degrees less on the exhaust. They will probably want to put the lobes on a 114 degree lobe separation angle.

Give them a call and explain what you are doing including using a log exhaust manifold and see what they recommend.

 

[Firepower354]

Maybe this would help, keeping the trios split? Some pretty tight thick-wall 1-1/2 bends are available.

 

[MeanGreen&Fireball]

Maybe this would help, keeping the trios split? Some pretty tight thick-wall 1-1/2 bends are available.

Thanks firepower, I’ll have to go look to see what aussiespeed has. Our friends from down under always have neat upgrades to the ford 200ci.

 

[MeanGreen&Fireball]

Schneider will grind you any profile you need.
If you want to push to 5500 then have them make a profile with the .050" duration closer to 214 degrees on the intake and a few degrees less on the exhaust. They will probably want to put the lobes on a 114 degree lobe separation angle.

Give them a call and explain what you are doing including using a log exhaust manifold and see what they recommend.

Pmuller9,

I decided to build my 250 instead of the 200.
Here is what Schneider recommended for a turbo 250 application. I wanted something that will make good mid power but top out around 5,000. I advised that I would be running my stock rockers with 1.5 ratio. I also wanted something with a fair idle and vacuum. Does this look like a good selection in your opinion?

I’ve also read where people run stock 1969 302 springs but I’m unsure of the lift capabilities of that spring.

 

[aussie7mains]

IMO for the 250, keep the cam stock, springs you will need, the boost will allow the engine to rev out better, the main reason a 250 wont rpm, is the poor breathing that a log head gives. So when 23psi (abs) manifold pressure is applied, it can now breath. So as long as springs will allow 5000rpm, there is no reason why a stock cam will stop it. This is what people here do for the 250s (usually crossflows) but precrossflow is similar. The 250 has abundant low down torque, so boosting to get some top end really helps. I run a blown 200ci crossflow with a tiny cam, (see elsewhere) it will rpm to 4500rpm (as far as I let it) there is no tailing off of power at this rpm. Stock cams give best street performance, especially with a slushie.

 

[pmuller9]

Pmuller9,

I decided to build my 250 instead of the 200.
Here is what Schneider recommended for a turbo 250 application. I wanted something that will make good mid power but top out around 5,000. I advised that I would be running my stock rockers with 1.5 ratio. I also wanted something with a fair idle and vacuum. Does this look like a good selection in your opinion?

I’ve also read where people run stock 1969 302 springs but I’m unsure of the lift capabilities of that spring.

The Schneider cam specs are exactly what I previously recommended for the 200 but the 250 will respond to the same specs at a lower rpm.
You will get a very strong midrange and the shorter 208 degree exhaust duration along with the stock log head and log exhaust manifolds will cut the power band off close to the 5000 rpm mark.
The idle will have some lope to it depending on how low you set the idle but the with no .050" duration valve overlap the vacuum will be good.

Before you can decide on valve springs you will need to know what the retainer height is.

A turbocharger has a very different response to camshaft profiles than a positive displacement supercharger.

 

[MeanGreen&Fireball]

IMO for the 250, keep the cam stock, springs you will need, the boost will allow the engine to rev out better, the main reason a 250 wont rpm, is the poor breathing that a log head gives. So when 23psi (abs) manifold pressure is applied, it can now breath. So as long as springs will allow 5000rpm, there is no reason why a stock cam will stop it. This is what people here do for the 250s (usually crossflows) but precrossflow is similar. The 250 has abundant low down torque, so boosting to get some top end really helps. I run a blown 200ci crossflow with a tiny cam, (see elsewhere) it will rpm to 4500rpm (as far as I let it) there is no tailing off of power at this rpm. Stock cams give best street performance, especially with a slushie.

Thank you aussie7mains

 

[MeanGreen&Fireball]

The Schneider cam specs are exactly what I previously recommended for the 200 but the 250 will respond to the same specs at a lower rpm.
You will get a very strong midrange and the shorter 208 degree exhaust duration along with the stock log head and log exhaust manifolds will cut the power band off close to the 5000 rpm mark.
The idle will have some lope to it depending on how low you set the idle but the with no .050" duration valve overlap the vacuum will be good.

Before you can decide on valve springs you will need to know what the retainer height is.

A turbocharger has a very different response to camshaft profiles than a positive displacement supercharger.

Awesome… thank you
I’ll also take a look at my retainer height

 

[pmuller9]

Awesome… thank you
I’ll also take a look at my retainer height

Did you get a chance to check the retainer height?

 

[Ultra]

Since you are new to forced induction, I would suggest you get Maximum Boost by Corky Bell. It does a good job of covering turbocharging and has some of the equations for the various systems. It will give you a reasonable base line. I'd also suggest you take a look at what guys are doing with japanese L6's like the nissan L28ET, RB20/25/26 and the toyota 1jz/2jz engines. I only suggest those because that's where I have been the last decade. Those engines all came factory turbocharged and those guys have done and tried everything. Also, the aussies have all those engines and the ford sixes, so there is plenty of stuff to read online that they have tried. The single biggest thing for me when deciding on what to do with a turbo engine is, how much power do you want to make? That basically ballparks you into what frame size turbos you need to be looking at. The plus side to these american engines is they all have big displacement compared to the japanese engines. So getting a turbo spun up is pretty easy.

The webpage isnt working for me at the moment but you can check out Borg Warners matchbot. It has a decent computer I have used in the past for estimating what power you might expect to make and it plots out how many lb/min of air you'll be moving on the compressor maps of the various turbos they make. Granted you need to know a fair amount of info to trust the numbers it spits out at you.