Hotside cold side.

[reed_67]

IS there any difference on the dyno pulls with a hot or cold mounted S/C?
If so what would be the reason?

[gludlow]

All things being equal (which they never are ;-) a hotside or Coldside dyno run would be about equal. It's just a matter of boost level.

Now, most hotside kits include an intercooler. From what I've read, the intercooler may increase your HP on a dyno run even at the same level of boost. I guess that's because it's running cooler? Honestly I'm not sure why.

The biggest different between the Hotside and Coldside is your maximum power level. You can get 220 out of a coldside kit, a hotside the limit is the strength of your engine internals and compression ratio. 250, 300, 350WHP? Of course, anything over 240 is going to require custom work on the engine of some type. 300+ requires a whole new clutch, rear axle, totally rebuilt engine, etc. Huge $$$, might as well buy a used vette ;-)

[FormerDatsun510Man]

I wouldn't say Hotsides would go 300rwhp or 350rwhp :). The most ever recorded was one run at 300rwhp while I was at BRP. Admittedly, that was sort of a dyno queen run. Realistically, the upper limit on the intercooled Hotsides is around 260-270rwhp with a built engine to handle it. I'm running the upper limit on the intercooled Hotside setup for a stock engine at about 240rwhp. This is the same boost/pulley ratio that used to give my setup 220rwhp, however improvements with the efficiency of the setup has gained it 20rwhp. Those improvements weren't cheap for me, but the good news is that most of them are standard on the new Hotside kits. The other thing is I am running the Stage One Tuning HFI manifold, which is similar to the concept of the Coldside intake manifold.

Bill

[Satisaii]

The coldsides have a bit less complexity in the routing of the intake air. This leads to a smaller volume of air between the engine and the throttle body, which gives you better throttle response and a more "stock" feel when driving.

With a lot more cost work and cost (think about doubling the cost, that is about where I am at with R&D) you can get a hotside to make more power. I also carry a full set of tools in my car in case I need to fix any problems that might come up on a trip.

If I had to do it again, I would take a coldside kit, up it to about 225 hp, and forget about it.

[reed_67]

I've heard with having a blower on the hotside means you have to be careful about what type of headers you can use. Not sure if there is any truth to that or not.

[Satisaii]

That is true, but I can't remember which one it is.

[FormerDatsun510Man]

The Racing Beat 4-1 stainless header is the one that will not work with the Hotside because the #4 primary has a hump that would hit the blower. The older Racing Beat 4-2-1 ceramic coated header and JR header will work, as well as the stock exhaust manifold/header.

Bill

[reed_67]

I can see the intake being in the way of the blower if you mount a cold side I guess the plus side would be that you might not have to mount an intercooler, I’d still mount one though. 225 WHP would be awesome even though my goals are not that high I would not be complain.


:party:

[Steve in VC]

Is the difference in throttle response between hot side and cold side caused by the increase in plenum volume? A cold side has almost none, so can increase cylinder pressure almost immediately. Hot side has a a larger volume to pressurize, so there is a lag. Add the additional "plenum" volume of an air to air intercooler (and piping) makes the lag even worse.

If so, it sounds like the ideal is to rotate the cold side supercharger 90* so the output is pointing at the intake, place a water to air intercooler between the supercharger output and the injectors. Include the intercooler volume as part of the plenum volume - no impact on throttle response.

The intercooler will add a bit of loss due to air resistance, but should be offset as increased air density reduces boost pressure, requiring less power to drive the supercharger.

A little knowledge is a dangerous thing - what am I missing?

[reed_67]

I'm not sure but as far as I know blower's do not have any lag because they are always spinning, so I would think that there would be no difference in throtle response.. but I've been wrong before...

[FormerDatsun510Man]

An even simpler solution to intercooling the Coldside would be to drill out some holes in the existing manifold to fit some Laminova style cores. I think this was discussed a while back. The problem I could see with redesigning the manifold so that the outlet of the supercharger is pointing towards the intake ports (i.e. a sidedraft style) is the flow may no longer be as equal to all four cylinders. With it directly flowing towards the intake ports, since the outlet is not as large as the distance across all four ports, likely the ports that are facing directly in its path would get more airflow than the other one(s). With the current setup the air exiting the supercharger first hits the bottom of the manifold and then has to fill it up flowing outwards from that point. In other words, it fills the plenum with air and then the pressure flows the air equally outwards and to the intake ports.