I have an s4 in a SA running on a Dellorto. I just picked up a S5 turbo off ebay and want to start playing with a boost project to eventually be put in my REPU.
I started thinking about blow though with the Dellorto.

Tell me to quit jerking around and pick up some S4 intake manifolds and a stand alone before I go building a hand grenade.

-billy

 

Well, that's certainly what I would do; the S4 manifolds and stuff. I lost a lot of faith in dellorto when my Hitachi outperformed it. Then I put in bigger jets and hello power!

 

Perhaps I should clarify. The RB prepped dellorto was never intended to be installed on a stock '74 REPU engine with its nearly streetport sized ports as stock. It was sized and jetted for the port size you'd find in a '76 Cosmo, nitrided R5 13B, or a 12A (with 13B rotors etc). The dellorto did pretty well on the stock ported R5 13B in my REPU until I did a street port. Then it only had power between 2k-4k. Above or below that sucked a lot (heh, not literally). Then I put a stock jetted '77 Hitachi carb from an RX-4 or whatever on it and it was much better through the RPM range, but the slight powerband from 2-4k wasn't there anymore. The secondaries sure were nice though. A simple jet swap to RB's recommended 105 for '74 sized ports in the primaries took care of that. Now the carb feels very nice on the engine and doesn't run out of breath until 7k or so. I'm also using a '79 12A air cleaner assembly so it would most likely breath better if I switched to a free flowing aftermarket assembly. I'm glad my dellorto went to someone who will appreciate it.

 

Quit screwing around and go with fuel injection and a stand alone. It's probably a more expensive route but it'll be SOOOOOOO worth it in the long run.

http://www.kyrotary.com/rrxp689/P3180057.JPG

 

if youve got a large budget, then go with a aftrmarket intake manifold, individual throttlybody setup, HALLTECH OR MICHROTECH for engine management, nice stainless steel exhaust manifold, big wastegate, nice big t4 style turbo, new fuel system and exhaust system, you will be good to go!!

or if your on a limited budget (like most of us are) then the s4/ s5 turbo blowing through the dellorto with a locked dizzy , upgraded fuel system set @10 psi will run good and be reliable without breaking the bank!

 

This dellorto lived on a bridgeported 4 port 13B and then made its way to a bridgeported 12A with some slight modifications. It now runs on my s4 stock port. I have not changed anything from when it was on the bridge A motor. It is not setup how RB delivered it.

That is not the point though. The point is that I need more evidence to stray away from the blow though and get a FI setup for the turbo project.


-billy

 

here is some blowthrough examples for you to check out



http://www.rotaryshack.com/CustomPro...stProjects.asp
http://www.rotaryshack.com/CustomPro...0gxl/85GXL.asp
http://www.rotaryshack.com/CustomPro...uto/84Auto.asp

 

Ah, so it's been modded for a freer breathing engine. Tough call. If you're into DIY, you could try a MegaSquirt and S4 manifolds etc.

 

Want to turn the boost up but not rejet? Want to drive all year round and not rejet (assumes you live where the climate changes)? Want to change elevations and not rejet? Once the standalone is tuned it's a set and forget deal. There are also a ton of features that come with a Haltech for instance. Want to have automatic control of that electric fan? Secondary rev-limiter/two-step? Idle control? Closed loop? Built in boost retard? Built in split control? Etc, etc, etc.

 

Want to head me into the direction of modifying the carb for blow through? I am sure I can do the work myself. Just not sure what all would need to be done.

I like the fact of tune and forget. I also like the fact of controlling other aspects with a stand alone.


But doesn't a blow through setup scream old school like the chassis the setup would be run in?

-billy

 

my halltech doen NOT compensate for altitude, i know the motech has a second map sensor straight to atmosphere to help but it does not compensate for air density...
as far as the other options you mentioned, yah your right plus you missed the traction control feature, built in boost controller, data logging ,aux outputs to name a few

 

The Haltech E6 series can compensate you just have to turn on the barometric correction feature.

 

yah it does have the feature but it dosnt correct enough!

 

To be honest I've never played with the correction factor, leaving it locked like the Haltech manual asks you to do. Isn't there a correction map that goes along with it giving you the ability to determine the correction factor? Thought there was.

 

I recently found a 45dcoe throttle body FI set up from weber that I am thinking would be ideal for such a setup, Have you guys seen/used/heard of it? What is your opinion of it?? What would work better considering I already have a manifold that it would bolt to??

ps keep talking, this is a subject i am curious about so I am learning a lot from your comments, Thanks.

 

Well it seems to have turned into a haltech thread

Here is my argument.

Is EFI more easily tunable? Yes.
Does it cost your left arm and a child? Not all of them. (MegaSquirt)
Can a carb be boosted and make good power? Yes.
Will Robert ever share his carb mods? No. J/K
Is either one better than the other? Each has its pros and cons

Both are viable options for boosting a Rotary. I have a few books on order that will be here next week. I intend on learning more about turbos and the way all the other systems work in conjunction with them. I have a few different projects. One will get a boosted carb setup and one will get a MegaSquirt (I like the open source, DIY aspect.) I think that boosting carbs is kind of an old school deal. FI does not become the end all solution for everyone who want a turbo setup.

-billy