FI options: Turbo or Supercharger
 

Hi guys,
I'm trying to get a rough plan and mod list for my 86 and would like to get some opinions on the two different FI routes(definitely will do one).

My end goal for power is around 325-350 Horsepower and this will likely be my daily driver for a little bit but will get workouts on track, hill climbs etc.

Personally I love the lure of the turbo, efficent power and a blowoff noise, who could argue with that. But i'm a little concerned about the heat produced by dding, a less linear power curve and honestly i am a little overwhelmed by options and setups available, so any help with the best setup for my goals would be great.

The more responsible side of me is pulling me towards a supercharger, specifically a Harrop supercharger, mainly because they are local to where i live and also seem to give reliable results. I like a linear power curve for DDing however i am a little concerned whether a supercharger can reach my goals, even with an e85 fuel upgrade and tune.

I will likely being doing exhaust mods, after market headers and catback if i get the turbo kit. Just a catback if i get the turbo kit.

I am happy to upgrade fuel injectors and run an e85 tune however ideally not run on e85 all the time, change to e85 for the more intense use.

Thanks for your help guys!!

TL;DR
Goal:325-350whp DD/Track car
Question: What forced induction route suits that goal?

I think you know which way to go!

gives you somewhat an idea

turbo is funnier always, and i m saying this with an unrestricted hks supercharger

From purely an engine reliability stand point a turbo can be setup to be much easier on the engine. Turbo has a lot less parasitic drain on the engine, and less load on the engine so you can make more WHP at the same crank HP, and with much less boost needed. heat issues with a turbo are a concern but if its a pure DD it wont be a big deal.

To have any chance of being somewhat reliable on stock engine 300whp is the max for a supercharger 325whp for a turbo. Even then its pushing it. but depending how often you are actually using that power.

How a turbo makes power (when/where/how much, lag etc..) is way more controllable compared to a supercharger, a lot of it is dependent on the size of the turbo and you can also run boost by gear or boost by rpm to control this more as well. Supercharger will always have the same general "curve" you can only make it bigger or smaller by swapping pulley sizes.

also keep in mind with turbo lag, even if you see a turbo making full boost at 4000rpm if the pull started at 3500rpm it took 500rpm to spoolup, if you are driving normally and downshift to 5k all of a sudden to start a pull it wont be making the power the dyno showed at exactly 5k right when you downshift, it'll take a second to spool up and you probably wont be "matching" the dyno plot until 5500rpm.

Supercharger is entirely linked to rpm and throttle opening. they are incredibly responsive and you will always be "matching" the dyno plot at wot. A positive displacement like harrop, edlebrock, cosworth, sprintex they can make a lot of boost down low very quickly and instantly as soon as you get on it no waiting time but become less efficient top end, the powerband they make is very fun and enjoyable and even when casually cruising DDing you will always be utilizing some of the extra power in the mid range. but that instantaneous low end torque is also what snaps rods. They make the car feel like it has a strong NA 3L V6, less of a "turbo kicking in boost" feeling.

centrifugal sc is the option many like to go because they lack low end and eventually at high rpm start building some great boost/power. They can have a lot of good applications for track/autocross cars, but this is my least favorite option for a DD, a turbo can do anything that can do for a DD but better, just set it up and control it to your liking.

Turbo does not pull power on the crank but it is a restriction on the exhaust flow. My preference would be free-flowing exhaust and an efficient supercharger over turbo.

Turbo

Turbo generally requires more expensive support modifications for heat management. I would not ignore those requirements. If you are going to aim 325-350whp (which is significantly higher than a basic kit provides) without building the engine, I would recommend a special tune and boost control that reduces the torque at low rpm. If you aim maximum torque at low rpm without building the engine, blow up risk will be high. I wouldn't do that.

Depending on his budget there are solutions to fully fix and resolve any potential issues/problems a turbo at 325+whp would create. I agree for tracking the car it would require a lot of supporting mods. For DD and canyon carver the list is much smaller.

Well, that power level without built engine and proper cooling is not something I can enjoy even for DD. There is simply not enough reliability margin. But, sure, I can only speak for my car.

Turbo all day, for the noises alone

This is a bit misleading since you didn't also mention it as a con for turbos. A properly sized turbo makes target boost at an earlier RPM than PD superchargers and present more danger to the rods. PD chargers need rpm to increase boost too.

Also didn't see mention of the potential for turbo install/maintenance issues that can result is boost spikes. Boost spikes can destroy an engine quickly and gear-driven chargers don't have that exposure.

did you ever saw a log of a PD, at low. rpm and WOT?

Anyway, boost spikes are tames by a boost limiter, so if the tune is well done, turbo can be safer than PD

This is like debating boxers or briefs. There's pro's and con's to each but it really all comes down to personal preference.
NA=Commando
Turbo=Boxers
Root/Twin screw=Briefs
Centrifugal SC=Boxer Briefs
Personally, If I lived in Australia and Harrop was in my back yard, just for that reason alone...Harrop all day long. :D

I didn’t go into exact details, but outlined that the size, how it’s setup, and using boost controller for BBG or BBRPM can determine boost curve and give you complete control of it how it ramps in. Also I mentioned a typical turbo will take around 500rpm to spool up once at WOT, and who goes WOT under 5k rpm besides in 1st gear anyways. If your cruising in 6th at like 2500 rpm down shift as your going WOT you won’t instantly be at full boost even if your at 5k+ rpm after downshifting still needs to spool up (unless brake boosting), But yes if you go WOT at 3k rpm by 3.5k if you didn’t use a boost controller you could be making near peak boost.

My PD instantly makes 10psi at 3500rpm at WOT and slowly ramps up to 13psi at around 6500-7k, so not instantly at max boost but still making a lot of boost at low rpm, much different than a centrifugal charger. And with zero lag or spool up time it comes on instantly directly correlated to throttle opening.

There is a reason car manufacturers usually use turbo over supercharger. Once setup right, it’s way better. Never said It was easier to setup correctly though.