Different jetting with racing beat exhaust?
12-08-16, 08:09 PM
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Different jetting with racing beat exhaust?
Hey Everyone, Its been a long time since I have posted anything on here but Ive got a couple of questions. I recently put a racing beat exhaust system on my otherwise stock 12a and have been very happy with its performance. I am wondering if I should be looking at making some jetting changes on the stock carb in order to help keep things from running too lean? Its the racing beat race header and dual system all the way to the back. Does anyone have any input on what changes, if any, should be made to the carb?
12-09-16, 07:19 AM
#2
Waffles - hmmm good
iTrader: (1)
Strip the ratsnest (if you still have it), hog out that nikki and do a DFIS ignition on it. You will go
from 105 hp to about ~150 hp easy and have a lot of fun doing it. It almost a 50% increase in
hp without cracking the keg. You may want to throw in an electric fan and of course will need
a better fuel pump solution as well.
from 105 hp to about ~150 hp easy and have a lot of fun doing it. It almost a 50% increase in
hp without cracking the keg. You may want to throw in an electric fan and of course will need
a better fuel pump solution as well.
12-09-16, 09:00 AM
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Strip the ratsnest (if you still have it), hog out that nikki and do a DFIS ignition on it. You will go
from 105 hp to about ~150 hp easy and have a lot of fun doing it. It almost a 50% increase in
hp without cracking the keg. You may want to throw in an electric fan and of course will need
a better fuel pump solution as well.
from 105 hp to about ~150 hp easy and have a lot of fun doing it. It almost a 50% increase in
hp without cracking the keg. You may want to throw in an electric fan and of course will need
a better fuel pump solution as well.
12-09-16, 01:20 PM
#5
If you read anything I've written within the past 2 or 3 years, when I say hogging out and boost prepping the Nikki, all boost prepping is, is making it so you don't have any potential boost leaks, but you don't have to worry about any of them if staying NA. All I'm saying is don't let it intimidate you to the point where you ignore some potentially highly relevant info. I mention this because any of my hogged out boost prepped Nikkis are perfectly fine on NA setups such as yours. The bottom line is if you modify your carb using my recommendations, you will end up with the best performing Nikki you've ever experienced.
With that out of the way, I'll answer your specific questions.
Because I don't run a stock Nikki with its huge air bleeds, I'd say the answer about using an RB long primary exhaust and needing to change the jets ranges from a maybe to a no. For one thing, you don't even have a wideband so how would you ever know? What's more is you don't know where to buy the right kinds of jets. Those weber air bleeds seen on the mazdatrix webpage being sold as jets with a .05mm step in size is awful for tuning. Do not buy these. Plus they are hella expensive and don't flow well when you are cornering hard due to their non-funnel shape (they are air bleeds after all, not fuel jets).
If you must buy jets, which I don't think you even need right now, get them from jets R us but note the sizes are not even close to what a stock Nikki requires. Hitachi carburetor jets and parts main jet slow air pilot kit Do you own any micro drill bits?
A stock Nikki primary jet size range is from 91 92 93 94 for their stock 20mm venturis. Your carb has 91 or most likely 92 in it.
Stock secondary jets of all modern 1st gen RX-7 Nikkis is all 160 and was sized to work with the stock huge air bleeds and stock vacuum secondary actuation. This does not need to be changed until you step up your game and want to go mechanical secondaries and need to get rid of the delay which most NAs never have.
The stock Nikki is not really a performance carb. The best way to get the best performance out of it that exceeds other carb choices is to follow our advice and perform the work yourself or get someone competent to mod it for you. These carbs are not easy to work on so it kind of weeds out the less capable.
Are you ready to step into the world of modified Nikkis? Jump in and don't look back.
With that out of the way, I'll answer your specific questions.
Because I don't run a stock Nikki with its huge air bleeds, I'd say the answer about using an RB long primary exhaust and needing to change the jets ranges from a maybe to a no. For one thing, you don't even have a wideband so how would you ever know? What's more is you don't know where to buy the right kinds of jets. Those weber air bleeds seen on the mazdatrix webpage being sold as jets with a .05mm step in size is awful for tuning. Do not buy these. Plus they are hella expensive and don't flow well when you are cornering hard due to their non-funnel shape (they are air bleeds after all, not fuel jets).
If you must buy jets, which I don't think you even need right now, get them from jets R us but note the sizes are not even close to what a stock Nikki requires. Hitachi carburetor jets and parts main jet slow air pilot kit Do you own any micro drill bits?
A stock Nikki primary jet size range is from 91 92 93 94 for their stock 20mm venturis. Your carb has 91 or most likely 92 in it.
Stock secondary jets of all modern 1st gen RX-7 Nikkis is all 160 and was sized to work with the stock huge air bleeds and stock vacuum secondary actuation. This does not need to be changed until you step up your game and want to go mechanical secondaries and need to get rid of the delay which most NAs never have.
The stock Nikki is not really a performance carb. The best way to get the best performance out of it that exceeds other carb choices is to follow our advice and perform the work yourself or get someone competent to mod it for you. These carbs are not easy to work on so it kind of weeds out the less capable.
Are you ready to step into the world of modified Nikkis? Jump in and don't look back.
12-14-16, 05:31 PM
#6
Is the ratsnest really a power sap, or is stripping it just to simplify tuning? I notice all these hogging out threads basically start with blocking everything off. I can understand opening it up for more airflow and fine tuning jets, but I scratch my head when it comes to removing the other stuff. I'm thinking for my low mile original car I'd like to do a header and exhaust like the OP and maybe a few minor tweaks to the Nikki but not go all out. I still want things like the manual choke, cruise control, and A/C to function as intended. My goal would be to open the hood and have it still look original (except for the header of course).
12-17-16, 10:46 AM
#7
The rats nest is used for emissions along with the air pump. Putting a header on will require removing the air pump and the cat should go anytime the air pump is removed. At this point the ACV can be also removed. At this point the rats nest really isn't doing anything.
My suggestion is to keep everything stock on low mileage car.
My suggestion is to keep everything stock on low mileage car.
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12-17-16, 04:41 PM
#8
You can remove everything as a unit from your stock setup and swap in high performance parts such as another stock manifold with the shudder valve and ACV removed. Also a channel cut and block all nipples except for Brake booster and some sort of PCV hooked to the correct nipple on the phenolic carb spacer (don't recall which one at this point but it needs to pull from both primaries).
This way all of your original rats nest and functional emissions parts are preserved.
A properly hogged out Nikki on an intelligently modded stock intake manifold can push your HP up past 130HP easily. Even t_g_pharrel, who didn't even measure his venturis when he cut them, use just hand tools like a drill and a dremel, has achieved something like 150HP.
All we're doing is converting a stock carb into a performance one that is better than aftermarket options.
This way all of your original rats nest and functional emissions parts are preserved.
A properly hogged out Nikki on an intelligently modded stock intake manifold can push your HP up past 130HP easily. Even t_g_pharrel, who didn't even measure his venturis when he cut them, use just hand tools like a drill and a dremel, has achieved something like 150HP.
All we're doing is converting a stock carb into a performance one that is better than aftermarket options.
12-18-16, 03:26 PM
#9
Thanks guys, I'd love to keep it stock, but I also bought it to be driven. It is painfully slow so maybe your suggestion of pulling everything off as a whole is a good idea so I can revert things should I ever decide to sell it. I'm not running a museum or anything.. I've put 7k on it and now it's time for more power.