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Old 17-06-2003, 01:36 PM   #1
UNV-323
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Cost-effective performance modifications: What can i do?

The following is a common question thats asked here...so lets make an example of it. The basics apply to any Astina.

cheers
Dan/rupewrecht

Quote:
Hi i really wana start modifying my car but money is the main problem. What can i do to my engine that would be cheap or even free. U know, some DIY jobs. And whatelse should i do to my engine that will cost me a bit of money. its a 93 Asinta 1.8 SOHC. Whats the go with the inlet to the airbox that comes from nowhere. its a sealed piece of ****...??? goes into the side of the airbox. So yeah could u guys please give me a big list of anything i can do to my engine and prices if possible. PLEASE!!!!!
okay thanks peoples!
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Old 17-06-2003, 02:08 PM   #2
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Check this topic out:

http://www.astinagt.com/forum/viewtopic.php?t=625


basically, the cheap(ish) ones are:
1) Cold Air Intake
2) Exhaust
3) Advance timing (will mean running Preimum Uleaded)
4) Sports air filter
5) Better spark plugs/leads (?)

To the mods (Rupe and Lantis) ==> Can we make the above topic sticky? We've had numerous questions on cheap performance boosts in the last few months. Mabey also rename it to something more meaningful.
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Old 17-06-2003, 08:46 PM   #3
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Drop in a K&N air filter - $100
Fit a performance muffler - starts around $150+
Use 98 octane fuel - hovers around 94c a litre up.
Use a fuel additive/upper cylinder lubricant like Morreys - $18 for a big bottle that'll last months.
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Old 17-06-2003, 09:01 PM   #4
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Also, a rising rate fuel pressure regulator (in conjunction with filter and exhaust) will improve performance. Anywhere from $250-400 depending on brand

what it does is supply more fuel (only when you put your foot down) by increasing the air/fuel ratio from 1:1 to 1:1.7, therefore putting more fuel into the combustion chamber and enabling you to go a little faster :wink:
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Old 17-06-2003, 09:19 PM   #5
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What rev count does the regulator kick in? Does it benefit the low end or really just the high end?
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Old 18-06-2003, 09:27 AM   #6
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the RRFPR works constantly, but really only supplies any extra fuel when you put your foot down. It replaces your existing fuel pressure regulator.

http://www.astinagt.com/forum/viewto...&highlight=fse
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Old 16-07-2003, 09:29 PM   #7
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Under Pressure!

Uz r amusing!
A RRFPR is used on turbo cars only!
A normal pressure Reg works via manifold pressure! The more negative pressure "idle" the less pressure in the fuel rail! (30-35psi) Then when u full boot it there is very little vaccum! Causing the diaphram in the reg to flex & cut of more fuel going back to the tank! Thus more pressure (40-45psi)
A Rising rate Reg is only used in high boost applications! When the engine is leaning off and you cant open the injectors any longer! Its just so u can get more out of an injector!
If ya ask me its a waste of money! Wait until the engine is leaning off to buy one!
Go to Jaycar to get a cheap mixture meter that patches into the original o2 sensor! Or u can pay heaps for a Gauge!
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Old 17-07-2003, 02:34 PM   #8
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Re: Under Pressure!

Quote:
Originally Posted by ezin
A RRFPR is used on turbo cars only!
i disagree. it can be used on any efi car, but is of most benefit on cars which require more fuel than standard - like turbos OR worked NA hondas etc
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Old 17-07-2003, 05:29 PM   #9
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LOL!!
Yeah only if the car is leaning out!
Otherwise your just emptying your wallet!
+ you can get a bosch adj pressure reg for cheaper!
Or even better, go to a volvo wreckers & rip one of the old ****ers! Fits in the pocket nicely so the price is right!
Dont forget about ur poor old fuel pump!
DO a flow test (AT pressure) first! U might need a new one!
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Old 17-07-2003, 07:05 PM   #10
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Ezin,
You ever heard the term Tip-In. Its all to do with the initial
opening of the butterfly and the extra fuel added at that point
and how it affects responsiveness. Much like a powervalve in
a holley Carby. Having a FPR which increases the pressure
increases the Tip-In and increases responsiveness. Its effect
after that is reduced as the O2 sensor reduces the pulse width
to try and keep the mixtures right. I have not recomended one
as a good economical upgrade but on the grand scheme of
modifications is one of the cheaper ones and does have a positive
effect on performance. No need to slam people.

Mal
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Old 17-07-2003, 07:20 PM   #11
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Not slaming Man!
Just ofering an opinion that might not have been considered!
The more we know, the more we can make beter informed decisions!
I dont know anyone in here! and dont know there level of expertise! So im just stating at the basics! Maybe it might help, maybe not! As long as we all find somthing to make our cars go hard its all good!
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Old 17-07-2003, 07:34 PM   #12
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When there are different viewpoints new ideas blossom. Good to be challenged but not to be flamed.

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Old 17-07-2003, 07:57 PM   #13
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Quote:
Originally Posted by ezin
Uz r amusing!
A RRFPR is used on turbo cars only!
Quote:
Originally Posted by ezin
LOL!!
Yeah only if the car is leaning out!
Otherwise your just emptying your wallet!
Maybe I am taking these a little out of context as they sound to be
challenges to me and not just opinions. Seeing I dont know you will
accept you didn't mean to slam. I'm just one for sticking up for my
mates.

Regards

Mal
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Old 17-07-2003, 08:09 PM   #14
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No Drama's Mal!

Im not a ****ing english teacher so some **** is bound to come out wrong!
Im just going on the info from all the courses ive done man!
If it helps any of u guys, then im happy!
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Old 17-07-2003, 08:50 PM   #15
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Just a suggestion here aswell man,just try keep the swearing to a minimum :wink:
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Old 17-07-2003, 08:57 PM   #16
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Sweet!!
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Old 30-07-2003, 03:13 PM   #17
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sound like old school learnings to me..

Traditional mechanical educators were the first to say... 'You need fuel' just change the fuel pump, or increase the injector size.' Old school...

So push fuel harder against the same fuel pressure regulator resistance and the same injector size to increase overall fuel delivery throughout fuel curve.. Or increase the cc rating of the injector so as to provide more fuel, again throughout your entire fuel curve. No tunability whatsoever..

Why not regulate what you have until this is not enough. This will depend on how hard you go power wise, although it's definantly the 'new school' way of modifying intelligently. The fuel curve is raised throughout the entire rev range to match the air flow characteristics (so you get your mixtures correct), and the additional 1:1.7 means that on throttle your responsiveness is about twice as fast, so your fuel system gets to where its supposed to be twice as fast. Like I mentioned in the FPR post over the road, 'the slowest thing to respond in an efi system is the FPR' and this is no accident. This was done to prevent an engine that was annoyingly responsive for the rest of society that do not want to race at the lights. :lol:

The thing with RRFPR's is when you adjust them at idle to stoiceometric mixtures required, it will only supply fuel when you thump the foot. What other fuel based mod can supply you fuel when you need it although remain steoiceometric when you don't? None. The advantage, drivability and max fuel economy.

Suggesting that a Adjustable RRFPR is only for Turbo Charged vehicles is like saying that a mandrel bent 3" exhaust is only used on Forced Induction applications.' At some stage of modification the engine will need additional fuel. The factory fuel system is rarely designed to be put to the test from a performance perspective.

Ezin. Your text regarding how a fuel pressure regulator operates is correct. But to suggest that only a forced induction car will require is not correct.

As vacuum drops - fuel pressure increases. To explain it clearly, at idle vacuum is at it's highest. As engine speed increases, vacuum pressure falls and fuel pressure rises. Why? Because FPR are vacuum/boost operated. The Vacuum line that runs to the top of them are controlling a diaphragm which connects to a shaft that blocks the return of fuel back to the fuel tank. So at idle when vacuum is highest it will hold the diaphragm/shaft back to allow more fuel to pass.

Acceleration :arrow: less vacuum :arrow: more fuel pressure.

Additional fuel is only required on fuel systems that are lacking.. or engine lean out issues.. True. Additional fuel is not going to provide power unless there is uncombusted O2 in air to be used. What Ezin is suggesting is that a NA car will never reach a point where it has uncombusted O2 and therefore will have no use for a RRFPR. This is not correct. So you have never heard of an NA engine running lean?

What I can say is that a forced induction vehicle has one additional benefit to the NA.. Boost pressure can be increased to higher levels and the factory fuel pump/injectors will cope. With this in mind the power advantages are certainly greater.

At Wide Open Throttle (WOT) whether a forced induction or NA, fuel pressure will be the same.... whatever that spring will hold against the maximum pressure of the fuel pump. Both NA and Forced Induction vehicles have the same problem regarding fuel delivery in higher revs. This has been the problem since the beginning of time. The issue of engine speed and adequate fuel delivery. There is untapped power to be had.

:arrow: As engine speed (rev) increases so does the demand for fuel. What decreases though is the amount of time we can ask an injector to remain open. So how do we supply fuel in higher revs? Fuel pressure forces more fuel from the same duty cycle. We are not talking about heaps of fuel when we talk about 'more fuel.' A little fuel goes along way...

What we have also found is an improvement in 'Atomization.' A slight increase in fuel pressure against a factory injector provided more power than a bigger injector supplied by a factory fuel pump. Why? Because improved atomization (fuel distribution) meant that there was a more surface area of fuel exposed to air. And you know what that means.

Cost Effectiveness? You just saved $150 x4 = $600 or so injectors and $400 for a decent fuel pump. You'll get alot more from your reg for $385RRP. So yeah, i think so.

Regards,
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Old 30-07-2003, 05:28 PM   #18
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Well what sort of pressure do you recommend that the BP 1.8L DOHC engine should have the FPR set at b4 it starts getting stressfull on the Fuel pump?
Cause i have been running mine at between 44-46PSI for the last 8 months now :shock: and would like to know if this is to much for my motor
I have a K&N pod filter,cool air induction,2 & quarter" sports exhaust,timing running at 14/15deg,and the usual aftermaket leads/spark plugs :P

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Old 30-07-2003, 06:36 PM   #19
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Yes! I quite like your answer GlobalAutomotive!
But im at a loss, Please explain!
A normal FPR has less pressure when there is vaccum and more once it reaches atmospheric pressure or boost pressure eg 10psi! But the difference in F/Pressure from atomospheric to 10 psi is the same pressure if measured on a gauge! Eg 44 psi at atomospheic and 44 psi at 10 psi!

I supose it all comes down to the design of the reg, + fuel pump pressure when the line is totally blocked off!

I thought you could by a RRFPR that has a specific rising rate! eg 45psi at 10psi and increases to 55psi at 20psi! Thats going to be usefull on a N/A car isnt it! unless u can cange the rising rate! U must be able 2!!!
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Old 31-07-2003, 10:52 AM   #20
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Toy Boy, your fuel pressure would not want to be at or over 50psi on idle, although you wouldn't need to get anywhere near that anyway. You would probably find 40psi to be adequate based on you current modifications. Just try turning it down and feel for power loss. I'd say you will probably gain from it.

Ezin, your a cluey guy. I know where your leading with this and Im impressed. Lets see if i can explain this without getting into poo poo.

The diaphrams resistance is the spring. The vacuum holds the spring. When the spring is released it pushes hard. In low performance setup's adding boost will push the diaphram harder against the force of the fuel pump pressure and this may create a slight increase in fuel pressure although the difference is nill to marginal with factory fuel pumps in low boost applications.

On the other end of the scale we have the High Performance Setup's...
In a setup like this the RR FPR has more room to play as it is part of a better fuel system.. It will supply more fuel pressure based on boost in high boost applications because the fuel pumps are considerably stronger than standard. Here the fuel pump fights the spring tension and pushes against the other side of the FPR diaphram in an effort to let fuel escape. Strong boost on the other side of the diaphram will allow fuel pressure will rise. So yeah in this sort of situation you are on the money regarding the relationship between boost pressure and fuel pressure.

Regards,
Adam
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