CAMSHAFT vs Turbo spool

[Mad_Trbo]

Ok Still learning and finding you cannot mix the world of NA with boosted in some cases.

What will the effects of a larger cam have on turbo spool and down low torque. Call the cam a 224/224 on 271 cubes.

I am in the process of tuning my car and thought with the extra cubes it would spin the heck out of the t66 I have. But what I am finding is that it seems a little laggy as when compared to my previous build with 231 cubes. Aside from moving from the more restrictive iron heads to a higher flowing aluminum head the camshaft is the only other change to the combo.

Are my expectations off, shouldn't this engine spin that turbo like no ones business. 10 lbs at 3k no problem?

 

[bison]

The lobe seperation seems to have the most effect on the stall speed. More = a lot more stall needed. Ive noticed with the cam i am running now im at 200 rpm less on the data logs down low than the the old 212 cam i had in there. It doesnt start making up for it until about 5300rpm. From there on it really hauls ass. Mine is 233ci. A 9.0:1 271ci with a 224@110 should still be no problem. If at 108 it could be a problem unless you have at least 3400 rpm at zero boost/vacuum. Cubes help out a lot though. Looking at the parts you are using id guess you plan on shifting at 6400-6500 and keeping it over 5200 minimum throughout the entire quarter pass and preferably at 5400 or higher. 10psi at 3k sounds like a 2000-2200 stall to me. You need a lot more converter. PM me if you want my rec. You need to get the engine over 5000rpm asap if your looking to maximize performance. A 66 is a tiny turbo for that applicaiton especially if 3 bolt. Is it THS or something?

 

[Mad_Trbo]

Looks like I got bad info.

 

[bison]

My first sentence should say more overlap which is a lower degree of separation. Dont want to confuse anyone.

 

[Nick Micale]

I would not be too quick to blame the cam?

From your post and items in your signature, I would look at a few other things.

You now have more cubes and airflow with the heads, but you may not have good, or sufficient port velocity.?

Also, the 3400 stall converter "should" be ok with a BB 66 turbo, but I have seen many AC converters with lot less stall than specified.

Further, the 96# injectors would take much "tuning" at low end for good spooling.

Just my perspective from where I sit! :biggrin:

 

[Mad_Trbo]

Injectors & Port Velocity

I would not be too quick to blame the cam?

From your post and items in your signature, I would look at a few other things.

You now have more cubes and airflow with the heads, but you may not have good, or sufficient port velocity.?

Also, the 3400 stall converter "should" be ok with a BB 66 turbo, but I have seen many AC converters with lot less stall than specified.

Further, the 96# injectors would take much "tuning" at low end for good spooling.

Just my perspective from where I sit! :biggrin:

Nick can you elaborate a little on the port velocity, is this simply going to be a problem inherent with low RPM's driving or is there something I can do with the setup I have to improve it.

As it relates to tuning, what should I be looking for. I am thinking make the timing event happen later(retard) in the cycle and pull fuel to get things spinning. So make this happen in the lower RPMs.

I have the ability to monitor EGT's for each cylinder so I can take it nice and slow but also go further safely than I could before. Why would you say it is going to be difficult with the 96'ers at WOT?

 

[vacuum 6]

I'm spooling with ease a turbonetics 66 BB with a 2800 12". It spools just like my TE60. See my sig for engine buildup.

 

[Mike Licht]

what is the lobe seperation of the cam? What is the zero boost stall of the converter (rpm where boost starts to build) ? What turbine housing on turbo? What spring in gate? and what boost controller?
Mike

 

[Nick Micale]

Nick can you elaborate a little on the port velocity, is this simply going to be a problem inherent with low RPM's driving or is there something I can do with the setup I have to improve it.

As it relates to tuning, what should I be looking for. I am thinking make the timing event happen later(retard) in the cycle and pull fuel to get things spinning. So make this happen in the lower RPMs.

I have the ability to monitor EGT's for each cylinder so I can take it nice and slow but also go further safely than I could before. Why would you say it is going to be difficult with the 96'ers at WOT?

Port velocity is a moot point at this stage, and without knowing more about your build, making a suggestion here is difficult at best.

First, I am not a "tuner" and rely on my expert Cal Hartline for programming and tuning our cars. I do know enough to recognize an issue, and know slow spooling can result if the tune is not proper.

Most of the time when I deal with combos and builds I have not personally supervised or done, the converter is the issue. It can take more than one re-stall or converter change to get it right.

You probably do not have a few converters on the shelf to pick from, or a lift to do the change in an hour, but that is where I would go first along with having an expert look at the FAST program. :smile:

Since every car and build is different, each has to be evaluated on its own specifics. Your build is specific and the combo is not a usual one.

 

[Mad_Trbo]

Info

what is the lobe seperation of the cam? What is the zero boost stall of the converter (rpm where boost starts to build) ? What turbine housing on turbo? What spring in gate? and what boost controller?
Mike

114 on the lobe sep
3100 zero boost stall
.87 but not sure on the turbine housing
3 - 4 lb spring in th
Manual boost controller _spring and check ball from Southeast performance

Was using an Apexi but felt no need for electronic, set it and let it be.

 

[Mike Licht]

I see nothing out of line with the converter, 3100 rpm should get that turbo going. Do you have a stronger spring for the gate, Since you are using a manual controller I would try a 12-15 lb spring, this will keep the gate from popping open too early and killing spool. If that does not do it like Nick said you need to look at the tune up. Do you have any FAST logs during spool up?
Mike

 

[Mad_Trbo]

Log file

Spring rate is a 3 - 4 lb spring, this is with no provision for boost control. A line straight from the compressor housing to the lower wastegate port.

My thoughts are no exhaust should be bled off until it reaches 4 lbs or so and it works, it just takes forever to get there.

Attached is a log of a recent WOT blast.

 

[DR BOOST]

Spring rate is a 3 - 4 lb spring, this is with no provision for boost control. A line straight from the compressor housing to the lower wastegate port.

My thoughts are no exhaust should be bled off until it reaches 4 lbs or so and it works, it just takes forever to get there.

Attached is a log of a recent WOT blast.

the spring is your problem... it will start to open before 3-4 lbs causing a slow spoolup.

put in at least a 14lb spring

 

[Mad_Trbo]

the spring is your problem... it will start to open before 3-4 lbs causing a slow spoolup.

put in at least a 14lb spring

Seems you are saying with a spring I am always going to have a gradual climb to my desired peak boost level, I do have a manual controller and I notice as I tighten this up I do see higher levels of boost earlier in the RPM band. Interestingly enough I put a vacum tester guage on the waste gate and it doesn't start opening until right around the prescribed 3 lbs. But I suppose the boost pressure is building and then exhaust pressure is building against the plunger so the combination of both causes the wastegate to open early. With that being the case I don't see how I ever reach my boost level.


So what I need to do is put my AVC-R back on. When I had it, boost was instand and steady. What I wanted to do was back off the additional gadgets, maybe XFI boost control is where I need to look next.

 

[Mike Licht]

With an external gate and a manual controller usually a "T" is put in the line between the turbo and the gate, that line runs to a regualtor and them back to the the top of the gate. The regualtor will add some boost pressure back to the top of the gate to keep it closed, the more you add the higher your boost. Call me if you need some help
Mike

 

[yullose]

Yeah... sounds like the WG is opening too soon.

I had a 66bb on my 234 with iron heads and it spooled like a stock turbo.