Making a beast 1987 p30

[Iamhunter]

I have a 1987 tiffin allegro/basement model with a 454 engine and turbo th400 tranny, I am currently redoing the entire electrical system then gonna start on the mechanics soon, I plan on installing a Holley Dominator carburetor on a Weiand track warrior intake manifold then some Hedman Streat headers. I'm curious as to whether or not anybody has ever installed a supercharger in a rv, I know there would probably be a clearance issue but that's nothing a little modification can't handle I'm sure. Then on to beefing up the cam an rollers etc.

Anyone with experience please let me know your thoughts

[code2e]

I have 3 thoughts. First, related to the clearance issue you mentioned. Headers will help the engine breathe for sure. Will also add a lot of heat around the engine compartment. Carb, intake and cam will add to your power as well as more heat to dissipate. I would suggest wrapping the header tubes with insulation made for the purpose to carry heat rearward.

Second, I love blowers. Can't imagine fitting a Roots type with carb and filter on top. Maybe an add on belt driven blower mounted along side the engine.

Third, I have installed several fuel injection systems. Edlebrock makes the Pro-Flo in several forms. Gets you programmable mixture and timing control. Well made system with factory support. It is a port fuel injection system. Includes the intake manifold. Some kits include cam & lifters as well.

Holley makes an add on throttle body fuel injection system that mounts on the intake manifold you choose. Still programmable mixture control.

Fuel injection allows you to choose power vs. fuel economy that a carburetor cannot. Make timing & fuel adjustments at different load levels.

Good luck with your project.

[D Gardiner]

Originally Posted by Iamhunter

I have a 1987 tiffin allegro/basement model with a 454 engine and turbo th400 tranny, I am currently redoing the entire electrical system then gonna start on the mechanics soon, I plan on installing a Holley Dominator carburetor on a Weiand track warrior intake manifold then some Hedman Streat headers. I'm curious as to whether or not anybody has ever installed a supercharger in a rv, I know there would probably be a clearance issue but that's nothing a little modification can't handle I'm sure. Then on to beefing up the cam an rollers etc.

Anyone with experience please let me know your thoughts

We have the later 454 with the throttle body injection. Can't say they are that bad, at all. The best part is going from sea level to over 8000 feet and never once needing to change jets.
On a 454 RV you will want to pick performance parts that compliment high torque figures just off-idle. You want grunt in an RV climbing mountains. Our 1995 engine has max torque at 1800 rpm.
The best thing we have is our 4L80E transmission. Gets us good off the line power with the 4.88:1 final drive and 19.5" rims, and still turn 2200 rpm at 60mph. Gets us close to 10mpg.
Lately, headers. Banks years ago found out that long tube headers worked well to extract the power. Even w/o a cam change we gained 80HP and 100TQ.

[yeloduster]

I had a 1988 P30 with the 454 and turbo 400 transmission. I too wanted more performance from my old engine. The 454 engine as installed in the P30 chassis was rated at ≈240 HP. That is pretty pitiful for a 454 CU engine!

Here's what I did to gain 100+ HP. I added Doug Thorley Tri-Y headers with 2.5" pipes and MagnaFlow mufflers. I built my own cold air induction system to bring cold air into the stock Q-Jet carburetor. This helped quite a bit but I could not tune out an off idle stumble with the Q-Jet.

I then added 1.9:1 full roller rocker arms. The stock cam barely opens the valves. I would have liked to install a better cam but I looked at the labor involved in removing the radiator....etc to install a cam and decided I didn't care that much.

I looked at the stock intake manifold and decided that it was a hindrance to air flow so I changed to an Edlebrock Performer dual plane intake manifold. The manifold and the rockers added enough additional air flow that the stock fuel delivery system could not keep up with the fuel demand at sustained WOT like climbing Colorado mountains. So I removed the mechanical pump and installed an inline fuel pump at the tank. That helped a lot but the engine would still run out of fuel on a long hard pull. I determined that the single needle valve on the Q-Jet could not flow enough fuel for sustained WOT. I changed out the carburetor for a Holley 750 CFM spread bore carburetor with vacuum secondary.

All this included tweaking the advance curves in the distributor, special air bleed and other tweaks to the carburetor and I don't remember what all!

It now ran pretty well! To make more power you add more fuel and more air and you get a hotter fire. Now the cooling system couldn't keep up on a HOT day on a long grade. I just slowed down if it started getting hot.

I then added a Gear Vendors Over/Underdrive Auxiliary Transmission behind the TH400. To my surprise the gear splitting feature of the GV added as much or more performance as all the engine mods combined.

You asked if anyone had done what you were proposing. I guess that I have...well sorta... I think your goals are commendable but your approach won't work well. The Holley Dominator carburetor and the Weiand track warrior intake manifold are designed for high RPM race car application. You aren't building a race car...you are building a truck! The stock 1987 454 truck cylinder heads won't flow enough air to support your carburetor and intake manifold.

I think you will find a more satisfactory combination if you aim for peak horsepower in the 4000-4500 RPM range and as much off idle torque as you can get.

I have had headers on several RV's and never found a need for header wrap. Header wrap will void the header warranty of any header manufacturer I know of! Ceramic coated headers claim to run cooler. I have them on a performance street car. They seem to work well.

[EyezOpen]

I'm down this road as we type here. After following a few very well established 454 builders along with carb and ignition guys I'm taking a very different path.

Rebuild the 850 Quadra jet, they meter fuel second to none.

Keep the stock intake, dual planes only outperform above 5000 rpm...a place you don't want to be with a heavy RV

Keep the peanut heads, I will have a 3 angle valve job done along with minor bowl blending. There a builder named Vortec Pro, what he does with those heads is amazing...all factory parts at that.

I've set my initial timing at 14 degrees, run manifold vacuum and limit my vacuum advance to ten degrees. This should be done by a experience tech, each and every engine is different and may require different setting.

Long tube 1 7/8 headers nothing fancy just a well made design.

These older gen 4 454 were and are severely choked down and stunted timing to say the least. It does not take much to wake them back up.