Yes, I searched. I'm having trouble finding exactly what I'm looking for... So any responses or links to other threads would be great. Let me explain the situation so the question is clear.

I'm planning on rebuilding over the winter. I have budgeted $4000 for the motor, plus $1500 for AI, and another $4000 for the single and a few fuel mods.

Current Engine Mods are:
PFC
Greddy SMIC
M2 Intake
Stock Sequentials (ported WG)
HKS Twinpower
3" Turbo-Back
Constant Oil Injection
3mm Mazda Apex Seals
Street Port by Rotary Performance
Supra Pump
Stock Injectors/Rail

I'm running 13psi every day and putting down 305WHP. The HP should probably be higher but the compression is flat 85s (remember 3mm 1 piece). Start-up hasn't been a problem. Also, the turbo manifold just started leaking exhaust. 55k on Rotary Performance motor, so it has lived a decent life.

When I rebuild, I am going to go single and install an AI system. My goal is to put down 350-370 HP everyday and for the motor to last at least 40k miles (hopefully more) under my lead foot. I also want high compression numbers. I'm leaning toward a T4 GT35R .86 A/R. I will upgrade the secondary injectors, install an FPR, and run 20% meth. Plus a good tune and I think I'm at my power goal under conservative boost.

My real questions are around the motor and porting options. I'm considering these two options:

1) Buy a new motor from Malloy (2mm 2peice seals) and send mine in as a core. But I'm concerned about the limits of the stock ports. $3650

2) Disassemble my motor. Send side plates and housings to JHB for cermet. Replace 3mm seals (maybe ceramic). Replace other internal wear items. Roughly $3500

The advantages of option 1 are I get all new parts and it is already together, plus I get it FAST (straight from Malloy).

Advantages of option 2 are I keep my porting, and upgrade the internal components to ceramic coating and seals.

What are the downsides of non-ported? What happens to a non-ported motor's torque as you raise the boost and respective power levels on a single turbo? I could open the new motor for porting, but then I'm shooting over my budget.

 

Pictures are gone, but the info is still there:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/pics-me-%40-track-my-10-sec-pass-128190/

10 second pass on a stock reman.

 

I run stock ports on my 500r and easily put out 400whp on a measly 15psi. My motor has about 30k miles on it and before the single swap, about 2k mi ago, I saw great compression on all faces. With all you are aiming for power wise the stock ported motor would be just fine. Though the porting is nice and will aid in decreasing lag. I see 15psi at about 3600-3700rpm and the 35r will spool just a bit quicker.

 

i think street porting is good for about 15-20% more power depending on the port. which is quite a bit. You could reach your power goals with less boost, or reach higher power at the same boost level, while decreasing spool time. There is a small loss in low end power off boost but i don't think it's noticeable. I went street port with my rebuild and single turbo conversion.

EDIT: when i got my engine done it was around $3500 including shipping. I got a large street port, 99 spec housings that has been resurfaced, 3mm seals. And actually my engine was so far gone that the only thing they reused was the centerplate, everything else was replaced so i ended up getting an even better deal. I was very happy with their work. I sent it to the guys in canada. i forgot the name of their shop but they are very professional. I was in the same situation as you, i didnt know if i wanted a reman, rebuild it myself, or send it to someone to rebuild it.

 

thanks guys!

 

the stock twins are more of a bottleneck than the stock ports are.

 

good info, I feel better about picking up a new motor and leaving the ports alone until it needs a rebuild.

Thanks!
Ian

 

I was making a bit over 500rwhp on a stock reman in my last FD and ran high 10's with it. Lee, Tearbo2, another forum member is making 700rwhp on stock ports.

 

Ernie wasn't that 700 rwhp figure done on a stock port Cosmo engine? If so even though it's stock port, it's still larger than what you get with the fd engine.

 

^^
Yes, but impressive none the less!

 

Ernie,

what did you notice after you started using a ported motor vs non-ported?

I'm not a drag racer, I prefer road course. So I'm concerned about the differences in Turbo Responsiveness.

Thanks,
Ian

 

Can anyone verify this claim? 15 to 20% more power just from porting? No change in boost.

 

Assuming you have an open exhaust system or one that is less restrictive than stock, I do not see this figure being unreasonable. Anything that increases the flow rate of the exhaust gasses will have dramatic impacts on power.

If your car is making 300 hp and you were to port it and get a 15% gain, that is an increase of 45 HP, I do not find that too hard to believe.

 

The percentage of increase differs depending on a lot of things. The question for you, is that percentage increase worth it?

IMO, I'm starting to look at these engines as disposable. Run the stock ports. When/if it blows, just drop another stock ported engine in it's place and go. If you blow a seal with a ported motor, it's just more headaches to deal with if you have one good housing and one bad housing. Same thing with machining the rotors.. It's a lot simpler when you just leave it stock and just expect to replace it.

Looking back at my old project, I wish I would have just bought a reman and been done.

 

Exactly --- I wish it was that simple with women too

 

I agree as well since you can usually run the same tune if its stock port unlike a streetport which is different everytime you build a motor. Thats the way things are though, you make more power, things get more unreliable and more difficult. And im about to put my T04R on my FC haha.

 

it all depends on what you want out of the car. there is really no limits to how much power can be made in either instance.Just get a bigger turbo and pump that much more air into it. But if you are looking for a specific HP number for a fun street car, i think getting there with less PSI is overall more reliable. I would rather run 15psi (safe on just pump gas) to get 400 hp then run 19 psi. for the same 400. And at the same time getting a quicker spool for a street car is nice.

For me i do my own tuning so retuning isnt that big of a deal, and hopefully this engine will last me awhile. If not then i'll prob just consider an Ls1.

If you plan on running 600+ hp drag car then you're probably also planning on redoing the engine again soon. how long do they last at that level? I dont even know. In that case stock ports are probably the simplest most cost effective route.

 

Yeah OK. That's the most powerful logic so far. Stock ports it is.

When I used to work on my MR2, I'd spend thousands getting the 3sGTE up to snuff. But at the same time, a buddy of mine would go through 2 5sfes (Mr2 Na Motor) a year, and still smoke my car.

He simply saw them as disposable and would spray dry 100 shots till they went pop. The 5sfe can be had for like $300 compared to a $2500 3SGTE.

 

You won't notice any difference if your road racing. A street port and stock are peaky in power. A bridge port will be the only way to have a very broad power band. So I wouldn't port it at all if I were you.

 

Port timing is still the same.


-J

 

^ Yes Port timing is THE MOST IMPORTANT THING The cosmo runners are stupid and make LESS POWER that is why Mazda improved the runner shape in the later 13B-REW as its FAR BETTER

I thought I would post up some specifications of a Rice Racing street port timing, pics and measures both with std rotor and RR special custom rotor.

Stock Port V's RR Secondary Port


Stock Port V's RR Primary Port


Modified Exhaust Port


IO = Intake opens
IC = Intake closes
EO = Exhaust opens
EC = Exhaust closes

RR Street Port Primary and Secondary Ports same on std Rotor (non beveled)
IO 15° ATDC
IC 67.5° ABDC
EO 78° BBDC
EC 60° ATDC


RR Street Port Primary and Secondary Ports same on RR special Rotor (beveled)
IO 22.5° BTDC
IC 75° ABDC
EO 78° BBDC
EC 60° ATDC


V's

Stock 13BREW
Primary
IO 45° ATDC
IC 50° ABDC
Secondary
IO 32° ATDC
IC 50° ABDC
Exhaust
EO 75° BBDC
EC 48° ATDC

**************************************
Here is a list of some port timing for other types.

Port Timing

IO = Intake opens
IC = Intake closes
EO = Exhaust opens
EC = Exhaust closes

US Model First Generation RX-7
IO 32° ATDC
IC 40° ABDC
EO 75° BBDC
EC 38° ATDC

European Model First Generation RX-7
IO 32° ATDC
IC 50° ABDC
EO 75° BBDC
EC 48° ATDC

First and Second Generation 6-Port 13B
Primary intake (Part throttle/cruise)
IO 32° ATDC
IC 40° ABDC
Secondary intake (Part to full throttle)
IO 32° ATDC
IC 30° ABDC
Auxiliary high speed ports (Full throttle above approximately 4000 rpm)
IO 45° ATDC
IC 70° ABDC
EO 71° BBDC
EC 48° ATDC

Second and Third Generation Turbo 13B
IO 32° ATDC
IC 50° ABDC
EO 71° BBDC
EC 48° ATDC


Racing Beat "Street Port"
IO 25° ATDC
IC 60° ABDC
EO 84° BBDC
EC 48° ATDC

Racing Beat "J-Bridge Port"
IO 115° BTDC
IC 72° ABDC
EO 88° BBDC
EC 57° ATDC

Mazda Factory Peripheral Port
IO 86° BTDC
IC 75° ABDC
EO 73° BBDC
EC 65° ATDC



Power and BMEP curves for NA SA port (BP), combination port (partial pp + bp, same as bp for comparison reasons), and peripheral port only
On open racing exhaust systems ***A massive 4% difference in BHP from BP @ 8000rpm under ideal conditions***

 

given your hp objectives stock ports as well as your turbo choice will work fine.

good luck,

hc

 

As a point of comparison, at 10 PSI on 99 twins I put down 310 rwhp and around 240 rwtq with a large port street ported motor and supporting mods.

Less boost should equate to less heat.

I'm going through the same decision right now also. I enjoy the street port as it pulls stronger at higher RPM and is more entertaining to drive but it has been so long since I've driven a stock port motor that I don't remember what its like anymore.

Anyone remember where the stock ports make peak power and torque?
At what RPM does the power / air flow start to fall off?

 

On twins based cars peak Tq is around 5250rpm and peak power around 6500rpm (recorded on road in 3rd gar)
With a T04Z peak Tq is about 5500~6000rpm and peak power 6600~6800rpm, with this turbo will hold power to 7800rpm and you can change gear at 8k (nothing after that is worth while)

Street port is about another 1000rpm on top of that (for both peak power and rev range) and volumetric efficiency is 10%+ higher depending on how good the porting job is.

It's worth it but requires an amazing amount of work to make a decent one that will give BIG gains over stock porting. If you like changing gear at 7000~7500rpm don't waste your time... stock is best for you

 

I started another thread on the actual build. My new motor should arrive Monday or Tuesday from Malloy. 100% stock, fresh from Japan.

Also ordered a 1.00a/r gt35r turbo kit.

Still researching A//I - But i'll likely allow my shop to use what they want with regards to that. So I think it will be an Aquamist unit spraying 50/50 water/meth at anything over 9psi.

400whp, here i come...