High horsepower street port
 

Ok, i've been doing some reading and looking around and have a couple ideas.

i know that gtorx7 made 230whp out of a streetport which is a great amount of power.

On the racingbeat website if you look at the holley intake kit for a 13bt they claim with a small streetport 230hp is possible.

so what i'm going to speculate that the rb holley intake flows better than the modified FD manifold that gtorx7 was running.

so if i was to build a 13bt with a large streetport a holley intake and optimized exhaust it would seem that 230+hp would be possible.



O and I'm sorry if it all seems a little jumbled up

Logan was running a 13B-RE manifold, not FD. There is a "big" difference.

That said, after poking around with an FD manifold, I'm surprised that junk can make any power on anything. The port shape is ruined by the need to clear the turbos.

If I could find good T2 end housings, I'd build another street port and use my modified S4 N/A intake manifold. I had a street port T2, stock (lightly ported) intake manifold, made 170whp on a Dynojet. Half-bridged it, power went down a little over much of the powerband. Much head scratching. Modified a S4 N/A lower to port-match to the T2 block, which was actually pretty easy, and the power came back, LOADS of bottom end, made 175whp on the same dyno but almost 1000rpm lower so the car accelerated much better. Peak power was at 6800, but the engine was breaking up a bit. At the track, it would keep going quicker and quicker until I was shifting it at 9200, so I suspect max power was actually higher.

So, I'm really curious as to how the N/A manifold would have worked on the street port combo.

Next engine is a 4-port 13B with a Holley-pattern throttle body. Probably going to be a street port, just to see what it does. Be neat if I could find a 13BT manifold to early 13B adaptor, but everything I see is pretty expensive and it goes the wrong way.

hmm.... ok, well i'm guessing the holley manifold will make more power than either because it was built with a performance mindset correct?

Just remember that in your initial example, you are comparing 230 WHP in GTORX7's car to 230 hp in the Racing Beat example. Using the standard 15% (actually I expect it is more) losses, the Racing Beat Mani setup looks to be about 195 WHP and the GTORX7 setup looks to be at the 264+ HP range.

I ran the Racing Beat Intake on my car with a 650 Holley DP and it ran very well, made decent power (192 WHP), but the Holley stumbled a bit in the corners and got dreadful race mileage. It was easy to tune, but slow as lots of stuff had to be taken apart and changed each tuning change. I would look at a stand alone and a modded S4 intake setup to make it easier to tune and run the car, but thats me.

Eric

that's a good point, RB has an engine dyno. GTO Rx7 has a chassis dyno

FWIW, the street port engine that did 170whp on a Dynojet, did ~151whp on Logan's dyno, and used fuel and made quarter mile ETs like 200 crank HP.

So, I wouldn't doubt if the fabled 13B-RE was really around 300 crank HP.

If you've never seen 13B-RE ports, they are HUGE.

possible? perhaps.

likely? that's a totally different ball of wax.

i think what you have to keep in mind with people like Logan is that aside from knowledge/talent, they also have resources (and i don't just mean money) to dissect every aspect of the power-game. as peejay mentioned, Logan started with an RE. also, if i recall, he modified the intake manifold and exhaust system a few times on that engine during the tuning process to get where he got. that's not exactly something the "average" backyard-guy can do on a whim.

i would say build the engine as best you can and if you're set on a Holley system, go for it. it can be converted to fuel injection later on if you so choose. just focus on tuning - whatever combination you end up with.

Just curious peejay, any pics of ur modded s4 manifold? I'm planning an itb set up but would really like to see your modified s4 manifold. This is jusy the kind of stuff that makes me love building engines, one person can build a custom manifold from scratch and get X power out of it, then another guy modifues a factory manifold for almost free and gets about the same power and possibly even a better tq band. Leaving others wandering wtf. Lol.

No pics that are much good. All I did was use a lot of epoxy (one of the JB Weld variants, I forget which) to completely fill in the aux port all the way up to the curve, which requires that you do it a little at a time and jig the manifold to rest at certain angles so it doesn't run out where you don't want it. Then it's just a matter of placing a T2 intake gasket over the thing and removing everything that doesn't look like a good port.

Here's me holding my used intake gasket on a mocked up 4-port 13B to show where there's room to drill/tap for new bolt holes and where the manifold's bolts would be flapping in the breeze... but you can see how much filling needs to be done. Oh, and you need to add a bit down under the primary ports to cover the air injection port, if you're using a T2 center housing. Or GSL-SE, for that matter.

Attachment 724943

I believe I also pulled the actuator bushings out and sawed the "knobs" off of the outside, which required more epoxy and a couple cover plates to fix the resulting holes.

hmmm the whole reason I'm thinking holley is its cheaper than going to FI at the moment and cars been down for 2 years so want to get back in it and have some fun at the track.
i understand that efi would give me better tunability and more power, but i'm on a slight budget at the moment and the rest of the car needs to get done first

A Holley that will properly work on a rotary is a little more expensive than EFI, if you've already got the fuel injection parts.

I wouldn't buy a used Holley, personally, because someone may be passing off a generic Holley as a RB part. There is a lot of modification done by Racing Beat to make the carb work properly on a port-per-barrel manifold. I haven't had one apart, but the air bleeds are made HUGE.

You might be able to get away with a standard carb with an open spacer under the manifold to tame the super-sharp pulses, but still, I've found that it's very common for used carbs to be "junk". Buying new is a (very good) option, but jeez, they're getting expensive even for the common ones. The last one I installed was $900.

Well, lookee what I found in a box:

Attachment 724944

Note the section under the primary ports to cover the air injection port on T2 center housings. Not required with a 6-port center housing (duh).

Attachment 724945

Port detail. I could have made it better, but I had time constraints and, well, it did end up working rather well.

How do they compare to Rx-8 6 port, ports? I recently(this week) built an engine with the primary ports pretty much copy and pasted from an rx8 6 port primary. the size looks like it went from a quarter to a half dollar. i left the other ports alone, primarys only... for now.. (s5 rotors/ecu)

the Cosmo primaries have the same timing, but the shape is different than FD ports, i think they are a little smaller.

the Cosmo secondaries are bigger though, so its closer to a streetported FD secondary.

the Rx8 i haven't had apart, but the intake area is 65% bigger, and the primary ports open earlier than the FD/Cosmo, so they should be bigger.

Im getting just under 200rwhp from a Stock SE 6 port engine, cant Imagine it would be that hard to get an extra 30 with porting.

Dyno sheet and more information?

i've heard a few times of a stock port breaking the 200rwhp margin but have never seen a dyno sheet

Crap i deleted my post.

I did say just under 200hp and Im not finished tuning the car. The dyno sheet is in a post in this section called 13b power band. Check it out. More ecu tuining and some intake and exhaust optimization and Ill hit 200rwhp

i went looking for the thread 13b power band and couldn't find anything. i found one thread in the first gen section called 13b powerband? but no dyno slips or much of anything else in there. could you post a link please?

want real power? just omit the intake manifold completely and mill the irons to all accept an injector each. :)


but really... wish more companies made modular intake manifolds to adjust the lengths with spacers to tune the runner lengths and possibly even runner diameters.

https://www.rx7club.com/naturally-aspirated-performance-forum-220/13b-powerband-999601/

there are 2 attachments with dyno sheets

lmao! that's funny, but not a bad idea...

175whp is worlds away from 200whp.

And the fix for the torque problem is so simple, you'll raise a few eyebrows. ;)

so whats the torque issue? An actual intake would help with torque, working on that.

178hp by the way, also note that it keeps pulling Id bet it would hit 180 just revving it farther. I could easily pick up more hp with a better exhaust, lengthen the intake a bit and get the afr and timing dialed in, its still a work in progress. Ive only even driven it twice so far.

all in all not bad for a 1985 stock engine

i'd be happy with 178rwhp. although you're right, a few tweaks here and there will make a big difference