few questions from a new fd owner?
11-09-05, 11:41 PM
#1
few questions from a new fd owner?
Ok i know yall all say search and ive been on this forum for a few years now, and have owned a couple of fc's(n/a) so i consider myself to have a little bit of knowledge haveing done all the work on my cars myself. I sold my 91 fc about 6 months ago and bought a 05 Scion tc, i hate this car as to one reason it has the worst 5 speed transmission i have ever driving i cant stand front weel drive car, but anyways im throu kicking myself in the but for selling my fc so im letting my dad take up payments on the tC and im getting a fd and have some questions. the car only has 49k on it and is stock except for a dp, boost guage and the cat being removed. Car is in remarkable shape for the asking price of 17,500.One of my questions is he said he never redlines it but at around 4k to 4,500k rpm's the boost guage says 6psi of boost, is this normal, and do these cars have limiters on them that dont let them excede the boost pressure of 10psi or can i only bring the car up in rpms and much as i want to untill the guage reads around 10, i just dont want to get it and redline and hit way hi boost and blow the engine. this my all seem kinda confusing but does the car have a limiter on boost pressure or do i need to be very very carful, and just dont redline it....
Thanx Justin
Thanx Justin
11-09-05, 11:48 PM
#4
Originally Posted by RX7Boy06
so if i keep on the throttle its not just gonna continue to rise above 10psi it should top out at this right?
11-09-05, 11:53 PM
#5
um i dont really know he just said he removed the cat so the engine would run cooler, but under normal stock car conditions it shouldnt go higher than 10psi? and if the cat was removed i just need to be very careful and keep a eye on the guage and dont let it excede 10 right? im completly new to turbos except for was i read in the faq and posts on here tell me as much as u can, and will a intake make the boost go up too?
11-09-05, 11:58 PM
#6
Originally Posted by RX7Boy06
um i dont really know he just said he removed the cat so the engine would run cooler, but under normal stock car conditions it shouldnt go higher than 10psi? and if the cat was removed i just need to be very careful and keep a eye on the guage and dont let it excede 10 right? im completly new to turbos except for was i read in the faq and posts on here tell me as much as u can, and will a intake make the boost go up too?
Just as a rule of thumb, when you make a change in the intake/exhaust of the car (restriction wise) expect boost to be slightly changed if not signifigantly changed.
11-09-05, 11:59 PM
#7
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Originally Posted by RX7Boy06
and is stock except for a dp, boost guage and the cat being removed.
If he's gone to the trouble of removing the DP and upgrading the exhaust system I'd be cautions.
Upgrading the ECU and intake is way easier.
I wouldn't drive the car hard. Have him drive you to a shop and get a compression test.
I'm sure since you've had FC's that you have experience with turbo's, but it not the FD if modded has a good chance to run lean. Which = blown engine.
Hope this info helps some.
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11-10-05, 12:01 AM
#9
so if it goes a lil beyond 10 than let of the gas right , i just dont want to have to limit myself by not being able to go beyond a certain rpm because of the fear of the boost going to high, i mean how do u do it with no gauge on a bone stock fd are they just designed not to go past 10 without mods?
11-10-05, 12:04 AM
#10
Originally Posted by RX7Boy06
so if it goes a lil beyond 10 than let of the gas right , i just dont want to have to limit myself by not being able to go beyond a certain rpm because of the fear of the boost going to high, i mean how do u do it with no gauge on a bone stock fd are they just designed not to go past 10 without mods?
Boost isnt really rpm determined. It takes a lot of variables to get boost, rpm, throttle position, load, intake temps...
11-10-05, 12:07 AM
#11
it has the stock muffler and stuff with everything else stock except for some sort of dp and removal of one of the cats, he said hes never exceded 4500rpms in the car(hes like 62 years old) and he said around 4k it says something of around 6psi on the guage, so do i need to put the cat back on and wat does a freaking down pipe replace?? i really have no clue wat it replaces or does and anything???? Thanx guys
11-10-05, 12:10 AM
#12
your first post says that you have a downpipe and midpipe (cat deletion). This can cause boost creep (like what was said earlier) and boost spikes (very very dangerous). The boost spikes won't be as pronounced as if you had a full system from turbo to tip, but they can still cause a momentarily lean condition, and poof, there goes your engine (if you're lucky, your turbines will be spared the chunks of apex seal). 6psi at 4k-4500 rpm's sounds like maybe a cracked vacuum line/malfunctioning solenoid. Spray some soapy water (use a very mild detergant that won't harm the vacuum lines) on the rats nest and see if anything bubbles, and make sure to wash it off so no residue is left behind. Before you purchase the car, take it to redline in 2nd or 3rd gear, but shut it down if boost goes anywhere north of 10psi, and have your passenger note the boost pattern (rpm's when: full boost is reached, transition (the little dip in boost), and full boost on the secondary turbo). If you do purchase the car, see if the previous owner can/will include the stock main cat. If he can, re-install it (unless it's clogged) to keep boost in check. If not, install a boost controller (manual or something along the lines of a Profec-B) and set the boost to 10psi. The boost controller will help eliminate the boost spikes. After that, install an aluminum radiator and an aluminum AST to help out the cooling system, and learn to drive the car before you do any mods. at almost 50k on a stock engine, you better try and talk him down a little on price, because you'll need to budget 5k+ for a rebuild.
11-10-05, 12:12 AM
#14
Originally Posted by RX7Boy06
it has the stock muffler and stuff with everything else stock except for some sort of dp and removal of one of the cats, he said hes never exceded 4500rpms in the car(hes like 62 years old) and he said around 4k it says something of around 6psi on the guage, so do i need to put the cat back on and wat does a freaking down pipe replace?? i really have no clue wat it replaces or does and anything???? Thanx guys
When you drive it, make sure it transitions at 4500. Thats the only way to test the turbos/turbo control system. Otherwise your just running on the primary. but if you cant ever reach at least 7psi, the secondaries will never come online.
11-10-05, 12:13 AM
#15
Originally Posted by RX7Boy06
it has the stock muffler and stuff with everything else stock except for some sort of dp and removal of one of the cats, he said hes never exceded 4500rpms in the car(hes like 62 years old) and he said around 4k it says something of around 6psi on the guage, so do i need to put the cat back on and wat does a freaking down pipe replace?? i really have no clue wat it replaces or does and anything???? Thanx guys
The downpipe replaces the stock pre-cat (it's the pipe that connects the turbos to the main cat). Mazda put it on to pass cold start up emissions, and it is wideknown as a huge source of heat under the hood. The installation of a downpipe will not affect what PSI you're pushing, because it doesn't improve the volumetric efficiency of the engine all that much, but it will help the turbos spool faster (turbos spool because of a pressure differential, if you reduce the pressure on the cat side of the turbos, the turbos will spool faster because there is a bigger pressure differential).
11-10-05, 12:16 AM
#16
so with not even 50k i already need 5k for a rebuild? this dosent sound quite right i mean the car from what he says has never been driven hard and he said everything that has been done to it has been done by alamo rotary, and he calls all the mods reliability mods so i guess tito hooked him up.
11-10-05, 12:17 AM
#17
Originally Posted by RX7Boy06
so taking away restrictions in the intake and exhaust u are letting the wastegate flow more and that alows higher boost psi?
not exactly. Think of an engine as an air pump. If you have a pump that has to breathe through a straw on each end, it will have a hard time sucking in and blowing out air. If you open up both ends (intake and exhaust), it will be easier for your engine to suck in and blow out air. The stock waste gate is used to bypass exhaust around the exhaust (hot side of the turbo) turbines to keep boost in check. If your engine can flow more volume through it (the Volumetric Efficiency), your waste gate will not be able to divert enough of the exhaust flow, causing boost creep. Alot of people port the stock waste gate to compensate for the increase in flow.
11-10-05, 12:19 AM
#18
Originally Posted by RX7Boy06
so with not even 50k i already need 5k for a rebuild? this dosent sound quite right i mean the car from what he says has never been driven hard and he said everything that has been done to it has been done by alamo rotary, and he calls all the mods reliability mods so i guess tito hooked him up.
11-10-05, 12:19 AM
#19
Originally Posted by RX7Boy06
so with not even 50k i already need 5k for a rebuild? this dosent sound quite right i mean the car from what he says has never been driven hard and he said everything that has been done to it has been done by alamo rotary, and he calls all the mods reliability mods so i guess tito hooked him up.
it's hard to say, how old are you again? If it's never been taken above 4-4.5k rpm's, there is probably a **** ton of carbon built up in the engine. Stock engines last anywhere between 50k and 145k (search high mileage, there was a thread on this last spring about how long your first motor/turbos lasted). If you're in your 20's/30's, you're more likely to drive the hell out of the car (like they were intended to be driven), and this will shorten the life of the engine considerably. The guy being old(er) is what probably saved this engine from going kaboom with those mods (downpipe and midpipe are sketchy on the stock computer).
11-10-05, 12:21 AM
#20
Originally Posted by Cgotto6
Boosted rotarys dont last long. They can last anywhere from 40k to 150k. It all depends on lots of things. Luck being one of them. If somebody said the car has never been driven hard, they are lying. Its as simple as that. These mods are reliability mods, but there are many more reliability mods that need to be done.
would you consider a midpipe a reliablilty mod? normal relibilaty mods are: Rad, AST, DP, Boost Gauge, and a driving school.
11-10-05, 12:24 AM
#23
Originally Posted by whitey85mtu
would you consider a midpipe a reliablilty mod? normal relibilaty mods are: Rad, AST, DP, Boost Gauge, and a driving school.