Hot Rod cams + Saleen S/C = no boost...

[Lupo222]

I posted this a month ago or so on another forum, but wanted to get some input from here.

I just recently installed a Saleen S/C on my 06 GT. I have Hot Rod cams and Long Tube headers...

After the install with the stock 4" pulley, i wasnt making any boost at all. Checked all the vacuum lines and everythings good. 18-21" of vacuum at idle in gear. Checked out with most other guys.

BBR and Brenspeed both told me they think it is the Hot Rod cams. They said their too aggressive on the exhaust side for such a small amount of boost. As they recommended, I bought the 3.4" pulle and KB BAP and now I'm seeing a solid 2.5 to 3 psi of boost with around 5psi above 5.5k rpms.

Anyone else ever have this problem?? I'm thinking about buying the Detroit Rockers FI cams if it is infact the hot rods that are causing this...

 

[StangPower05]

I run Hot Rods and longtubes with my Whipple setup and i havent lost a pound of boost. Many on here run the Hot Rods with all different FI setups and havent had any problems relating to boost. Thats a weird problem that ive never heard of.

 

[Lupo222]

well, doesn't the whipple make more boost on the stock pulley than the Saleen? They told me that it was a Saleen exclusive problem becaue the Saleen uses such a large pulley and only makes around 4-5psi with teh stock pulley. I've had a bunch of Whipple guys tell me they were fine, but haven't heard from a Saleen + hot rod cam guy yet...

 

[zuritausmc]

well, doesn't the whipple make more boost on the stock pulley than the Saleen? They told me that it was a Saleen exclusive problem becaue the Saleen uses such a large pulley and only makes around 4-5psi with teh stock pulley. I've had a bunch of Whipple guys tell me they were fine, but haven't heard from a Saleen + hot rod cam guy yet...

Why did you go from a 3.4 to a stock pulley? I was running a 3.2 pulley with hot rods and long tubes and seeing 9 to 10 psi so I lost a lb or 2 but thats it. Worked just fine. Heres the dyno (thru an auto as well)

 

[zuritausmc]

And I also switched to a whipple and on a 3.3 pulley i was seeing 9 lbs just for a comparison

 

[white05gt]

I don't know much about Saleen s/c but is your bypass working correctly?

 

[JeremyH]

Hot rods are restrictive to flow in the low/mid range with a twin screw once boost comes in, but not to the point where you wouldnt see boost, the problem is likely elsewhere.

 

[Lupo222]

i didn't switch from a 3.4 to a 4...i went from a 4 to a 3.4 in order to make boost. the bypass works properly. It lifts when I let off teh gas and goes down when I give it throttle.

I'm 99% sure its the cams...because i did see boost when I got the 3.4". I was thinking could it be something related to the cam phaser or the timing??

 

[JeremyH]

Boost reading at the manifold is a measure of restriction on your setup. With hot rods and a twin screw you would actually register more boost down low not less since the tight lsa is resticiting the flow of boost into the cylinders while the blower makes alot of boost down low in the rpm range and is trying to force it in.(this is why they arent a good match in the first place)

Not reading proper boost for your setup has no relation to the cam phasers, they could be locked out and it wouldnt matter, this and timing play a roll in power production not the blower making boost.

How much power did it make? maybe an issue of where your boost gauge is hooked up or gauge itself.

If not, the issue in the blower setup itself. Either bypass leaking by( most likely issue as they can fail). Belt, slip, pulley issue, or internal to the blower itself.

 

[8306gt]

Boost reading at the manifold is a measure of restriction on your setup. With hot rods and a twin screw you would actually register more boost down low not less since the tight lsa is resticiting the flow of boost into the cylinders while the blower makes alot of boost down low in the rpm range and is trying to force it in.(this is why they arent a good match in the first place)

Not reading proper boost for your setup has no relation to the cam phasers, they could be locked out and it wouldnt matter, this and timing play a roll in power production not the blower making boost.

How much power did it make? maybe an issue of where your boost gauge is hooked up or gauge itself.

If not, the issue in the blower setup itself. Either bypass leaking by( mostlikely issue as they can fail). Belt, slip, pulley issue, or internal to the blower itself.

Without wanting to sound like a smartass everything you have just told this guy is wrong except the part about the problem is most likely elsewhere. The camshafts having a tight LSA and overlap (this means intake and exhuast valves are both open at the same time) could cause boost to be less than expected. In other words the cams could be allowing the boost to be blown out the exhaust down low instead of pressurizing the cylinders. All of that said the problem is likely something else as others using these cams have not seen this problem to this extent.

 

[rford426]

Doesn't Redbaron have have hotrods or mutha thumpas

 

[UltraKla$$ic]

You can always get a "ghost tune" and act like you have cams. LOL

 

[JeremyH]

`

Without wanting to sound like a smartass everything you have just told this guy is wrong except the part about the problem is most likely elsewhere. The camshafts having a tight LSA and overlap (this means intake and exhuast valves are both open at the same time) could cause boost to be less than expected. In other words the cams could be allowing the boost to be blown out the exhaust down low instead of pressurizing the cylinders. All of that said the problem is likely something else as others using these cams have not seen this problem to this extent.

Yes open valve overlap can cause this slight loss down really really low (ie below 1500rpms where most power adders dont even generate boost yet) below what the rated rpm range of the cam is, but the tighter lsa also increases closed valve overlap(both valves closed at the same time) which restricts boost/flow on the intake side throughout the midrange (opposite effect of what you describe), I have seem it time and time again on multiple dyno graphs on different setups. The tight lsa is designed to bring peak torque down lower in the rpms to achieve more power up top and is not idea for power adders that generate full boost in the low/mid rpm range for this reason.

 

[Lupo222]

The bypass is working properly. Unless it can be bad and still raise and drop the plunger properly...

As for the boost gauge, its good. I had it dyno'd and they registered 3.0psi until 5.5k rpms where it went up to 6psi or so.

It was only with the stock pulley that it didn't make any boost (maybe .5psi). With the 3.4" it makes around 3psi, which if you figure the cams loose about 2psi and the LTs about 1.5, that puts that pulley around 6.5psi which is almost what it should be...

I did just put a tighter belt on but no difference really.

The car dyno'd 402rwhp with the 3.4" pulley and the hot rods and a steeda CAI.

So still no saleen guys with hot rods??

 

[tmcolegr]

2 questions - and if you already answered these questions please disregard this post:

• what belt are you using - specifically what part#
• Are you still running the Saleen supplied 76mm plastic guided idler pulley next to the P/S pump

 

[JeremyH]

So still no saleen guys with hot rods??

Did you not see post #4?

 

[nbk92]

The bypass is working properly. Unless it can be bad and still raise and drop the plunger properly...

As for the boost gauge, its good. I had it dyno'd and they registered 3.0psi until 5.5k rpms where it went up to 6psi or so.

It was only with the stock pulley that it didn't make any boost (maybe .5psi). With the 3.4" it makes around 3psi, which if you figure the cams loose about 2psi and the LTs about 1.5, that puts that pulley around 6.5psi which is almost what it should be...

I did just put a tighter belt on but no difference really.

The car dyno'd 402rwhp with the 3.4" pulley and the hot rods and a steeda CAI.

So still no saleen guys with hot rods??

My car with Saleen S/C made 465HP at 6300 RPM with 7.7 PSI. Check my signature below. However, I am changing my horrors out for Comp stage 2's with limiters, springs, and retainers. Check out my post titled Glowing Headers.

 

[Greg Hazlett]

Would have to check but aren't the Detroit Rockers pretty close to the Hot Rods? If so why would you want to go through the headache/cost of swapping in essentially the same cam?

My tuner told me the HR cams are not boost friendly and the stock cams will work just as well if not better than the HR's so I removed them and put the stock ones back in.

 

[Lupo222]

I saw post # 4 and responded by saying that I might be able to get close to those numbers with a 3.2 but i'm not sure.

I'm using a 107.3" belt as recommended by Saleen. Getting a little squeal and a lot with teh A/C on. I ran some water under the belt and it didn't stop. Got the tensioner pulley wet and it stopped. I'm thinking maybe my tensioner is going bad?? Time to upgrade...any suggestions?

Also, no I am not running the plastic pulleys. I heard bad things about them failing...

 

[tmcolegr]

I'm using a 107.3" belt as recommended by Saleen. Getting a little squeal and a lot with teh A/C on. I ran some water under the belt and it didn't stop. Got the tensioner pulley wet and it stopped. I'm thinking maybe my tensioner is going bad?? Time to upgrade...any suggestions?

Since you asked...

For your application I would recommend:

• Thump_rrr tensioner w/76mm pulley
• 90mm idler pulley next to the P/S pump
• V10 W/P pulley (improves belt wrap on the S/C pulley)
• Gates K061080 or K061080HD (Fleet Runner) Micro-V Belt - Both can be purchased through NAPA part# 25-061080 or 25-061080HD

Can you post pictures of your vacuum hose routing?