So I figured I might as well create a thread about my '88GT that I recently acquired. It currently has about 177K on the chassis and ~70K on the drivetrain. The 4.9 was originally swapped in another '88GT about 4 years ago, and put in this one last summer/fall. It is currently an auto with the 2.73 trans, and was converted to the '85GT look at my request by the previous owner. I will update this thread with any and all modifications/restoration I do. I plan on finding some way to restore the power lost due to my elevation (6000 feet) and a little more as well, most likely with a turbo, but I work slowly so that may be a while.
There is a lot of hidden HP potential in the intake manifold not seen to the naked eye .
The general consensus is that it adds ~20 HP. (I felt a noticeable difference with mine.) I'd always be interested in hearing your thoughts on the hidden HP potential.
------------------ Raydar 88 4.9 Formula IMSA Fastback Read Nealz Nuze!Praise the Lowered!
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11:03 PM
Boogaloo Member
Posts: 422 From: South Miami,Fl Registered: Sep 2009
Hey, I want to know about the "Hidden potential" about the Allante intake myself! Why not you share it with everyone here since this thread is about an Allante Intake swap. Of course if you can find one (no idea where I would get one if I wanted to go that route).
Fuel rail and alternator bracket installed, and test fitting the upper manifold to see what sensor wires I will have to lengthen. The TPS connector is different from the 4.9, so I will have to splice on the new connector. Also, the trans dipstick tube ends right under the front of the trottlebody, I will have to see if I can bend it out of the way.
I think I could use a bigger garage...
Diagram I drew for myself on the wall as I was taking stuff off the engine. The dist cap and manifold is also marked with cyl. no's.
Looks great! I like the paint also. I see that you have two valve covers with the oil fill. Most people are able to swap the front and rear valve covers if that interests you. Or put a breather vent on the extra, or leave it as is =)
When you're wiring up the TPS... The original 4.9 TPS has the wiper in the middle. The Allante wiper is on the end. (Sorry. I forget which end.) If it's wired up wrong, the tranny will shift very strangely, among other things. Don't ask me how I know this.
Worked some more on it today. Cradle cleaned up and installing poly trans mounts since the old rubber ones were torn up pretty bad.
Poly installed for rear suspension...
Oil pan gasket and trans filter changed while engine was in the air.
Went junkyard shopping today and went and got a 3.33 diff out of a '92 Seville. Was a huge pain to get it out while everything was in the car, but installing this diff changes my 2,000 RPM speed from 76 MPH to 70 MPH with my current tires. I had a 37/33 chain ratio and 3.06 diff giving me an overall ratio of 2.73, now I have a 37/33 chain ratio and 3.33 diff giving me a 2.97 overall ratio. The 2.84 diff has a sun gear with 38 teeth, the 3.06 has 34 teeth, and the 3.33 has 30 teeth and 20 tooth planets. All have 70 tooth ring gears and are interchangeable by pulling off the cover on the pass side of the trans. Per my calculations this will drop my 0-60 time by 0.25-0.30 seconds, and my 1/4 mile time by 0.40 seconds. I will re-tune the trans shift points at the same time I tune for the Allante intake. All possible ratios are shown in the last picture.
Now I have to figure out how I want to do the exhaust!
Thank you, that is exactly what I want to do with my 4.9/4T60E, I have a final of 2.73, and I think its just too low. While changing the chain to a 35/35 would be nice to make it 3.06, 2.97 isn't too bad. I just gotta find a 3.33 diff.
I was going to change my chain ratio, but I'll wait until I need to rebuild this one. I believe the Touring DeVilles and regular Sevilles all had the 3.33 diff. There were several of them in the junkyard I was at today. I just picked the one that had the most stuff pulled off and out of the way already, lol. Also got myself a new deville u-pipe to replace my really restrictive jacked up one.
I was a bit upset, because I did have it rebuilt, and since it had a 3.06 diff, I thought that was it, I didn't know the chain was a 37/33 chain. Gr. Oh well, I think I might change it when I have the 4.9 out for the 88 cradle swap.
Sorry for the long time between posts, I was down in Texas and florida for a while. Finally got the thing started today. I had to lengthen the wires for 4 sensors, the MAT, MAP, TPS, and the IAC motor. Since the TPS sensor had a different connector, I had to wire it up instead of the old one. Both connectors have three wires, and both had an "A", "B", and "C" marked on each pin, so I just matched the corresponding wires up to the new connector. It seems to work, but I still need to hook the thing up to my laptop to make sure it is reading correctly.
A few issues I ran into were the dogbone mount was in the way of the brake vac port on the upper manifold, so I had to cut that away. Also, the MAT sensor connector is just about touching the rear bulkhead, so there is not much clearance there. I still need to hook up the throttle cable also. When I started it it ran pretty rough (sounded like it had a wild cam) so I still need to set the timing as well. I have it running on the old 4.9 chip, once I get it timed I will start tuning for the Allante intake.
I ended getting an inline filler/cap so I can burp it just like the stock Fiero (the thermostat has the 1/8" hole in it).
Here's a top down view in the car. It is pretty messy, I still need to clean up the vac lines and wires, etc. I was just trying to get it started, and so cobbled it together with what I had on hand.
Still got to figure out the air filter part.
My inline cap coming from the thermostat housing outlet.
A vacuum line diagram I found from somewhere. ------------------ 1985 GT 2.8 MT 1988 GT 4.9 AT
[This message has been edited by NJD85GT (edited 07-24-2011).]
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12:20 AM
Raydar Member
Posts: 41116 From: Carrollton GA. Out in the... country. Registered: Oct 1999
Regarding the vacuum lines... All of the ports on the TB are manifold vacuum, EXCEPT the 2nd one from the TPS, on the top. It's ported vacuum. I ran that one to the lower canister fitting, and ran the 1st one (nearest the TPS) to the very top canister fitting (the diaphragm.) 3 and 4 from the TPS go to the FPR and the vacuum modulator on the tranny, as the picture shows. Both of my large ports on the side are capped off.
[This message has been edited by Raydar (edited 07-24-2011).]
Lets see if I can get this to work. Here's a sound clip of one of the first startups. Still needs to be timed and tuned, it's running really rich. Though I think it sounds awesome.
------------------ 1985 GT 2.8 MT 1988 GT 4.9 AT
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09:37 PM
Raydar Member
Posts: 41116 From: Carrollton GA. Out in the... country. Registered: Oct 1999
Thanks Raydar, I'll look over my vacuum lines and make sure I got the canister right. Where did you hook up the pcv valve?
There is a hose barb on the end or bottom of the plenum, near the map sensor. I connected my PCV valve hose there. I removed the large hex plug from the bottom of the plenum and installed another hose barb, and a right angle, for the power brake booster line. On the opposite corner of the engine from the PCV, I used a rubber elbow, plugged in to the corner of the valve cover, with one of those small parts store cone filters, Held together with a piece of metal tubing.
Edit - Just played the vid. Sounds good!
[This message has been edited by Raydar (edited 07-24-2011).]
Today I spent all day working on the car, sorry no pics. I installed the poly in the front, along with new dropped springs, shocks, and poly end links. What a PITA to do the poly up front, the rear was so much easier! Also put my new braided steel brake lines in and bled the system.
Turns out my new Allante alternator doesn't work, I took it in the be tested and it passed all tests, but it doesn't do jack in the car. I hooked up my old one and the voltage light came on like it should, so I know my wiring is fine. I have a new one on the way... After that I did my preliminary tune for the Allante intake, and timed the engine to 10 deg. for now. (May up it to 12 later). Took it for a very short test drive as I was running only on the battery, holy crap does it move in first gear!
I still need to do the idle learn and TPS learn, I will do that after I get the new alt. installed. I seem to have a little bit of a sticking throttle at idle, it likes to stay at 1000-1200 sometimes (I programmed for 700), I can move the throttle plate manually and get it back to 700. My fuel pressure is 42 with the engine off, no leaky injectors which is good, and about 36 at idle. Hooked up my laptop and I confirmed I wired the TPS correctly, though it shows 35deg at idle right now. Also have a few codes:
Code 15 - Open Coolant Sensor Code 52 - ECM Memory Reset Code 65 - C/C Servo Position Sensor Failure
So I guess I'll have to get a new coolant temp sensor (hope it's not the wiring, the computer showed like -40 deg temp). I'll have to go back and remove the cruise control codes on my next chip burn to get rid of the code 65 since I don't have C/C anyways. I also adjusted my pulses per mile for my new diff. ratio and tires, as well as my shift points. Still got to figure out the air filter soon too.
Nate
------------------ 1985 GT 2.8 MT 1988 GT 4.9 AT
[This message has been edited by NJD85GT (edited 08-03-2011).]
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12:00 AM
PFF
System Bot
katatak Member
Posts: 7136 From: Omaha, NE USA Registered: Apr 2008
I just sold my 88 XTC/GT to a guy in Brighton. He owns a tranny shop somewhere between Brighton and Boulder. He flew into El Paso last night and drove the car home - got there early this am! He said that the car ran great - got 24mpg running 80 plus! The XTC used to be Carver1's, I bought the 4,9 I put in it from Carver1, You have a Carver1 Fiero with a 4.9 that I installed in a guys 88 here in El Paso then Carver1 picked it up when we swapped it for a 3800SC! This Fiero world is a small one after all!
So I figured out my coolant temp sensor problem, turns out the harness was wired incorrectly and the head temp switch by No. 8 cyl was plugged to the ECM, while the guage sensor was in the spot by the thermostat. For now I bought a new coolant temp sensor and put it in the right spot with the ECM plug. I will modify it later to the 3-prong sensor so I can have the gauge as well. Also got my new alternator in, all I have left is to do the air filter. I will use the stock air can, modified a bit for bigger tubing.
I let my nerdiness get the best of me and went and did some analysis of the stock vs. Allante 4.9. I am not sure how accurate this is but it seems pretty close. Feel free to correct me if I am wrong, as I am still learning what everything does in the file. A lot of what is below I am guessing at.
I used the volumetric efficiency tables to compare the two, as to tune for the Allante intake I pretty much copied over all the stuff relating to fuel into the 4.9 file, and will fine tune the VE table later for my car. The base pulse constant was left alone for the 4.9 (183), since the Allante and 4.9 supposedly use the same injectors, and the ratio 4.9/4.5 is very close to 183/167 (167 for stock Allante). It was hard to find a good dyno sheet for a 4.9, but knowing that it makes 275 TQ @ 3,000 RPM and 200 HP @ 4,100 RPM, and knowing the torque curve is very flat (I also read somewhere that the torque close to idle was something like 220 ft-lb), I was able to come up with what I believe is a reasonably accurate torque and HP curve for the 4.9 from 2,000-5,000 RPM. Since the only major difference between the two tunes is the VE table, and the VE table is used to calculate mass flow rate of air into the engine, which is then used to calculate fuel, and fuel flow rate is directly proportional to horsepower, I took the ratio of the VE values at 100 kPa (WOT) and multiplied it by the stock 4.9 HP to get the Allante 4.9 HP. I then back calculated to get the torque again. The results are below.
What I see is a maximum of about 215 HP @ 4,300 RPM and a maximum of about 290 ft-lb at 3,500 - 3,600 RPM. This seems about right, as the stock Allante 4.5 was 200 HP @ 4,400 RPM and 270 ft-lb @ 3,200 RPM. There is a little bit of an odd hump around 3,600 RPM. Anyways, it seems that the Allante intake does nothing below about 3,200 RPM, but once you get into the range where it was tuned it helps quite a bit.
The timing looks to be advanced a few degrees at WOT for the Allante vs. 4.9, so a few more HP is probably gained that way. Not sure if my method accounted for that or not.
A note about the VE values from another website:
quote
The fuel table contains the Volumetric Efficiency (VE) of the engine. This is a percentage of available air that makes it into the combustion chamber for each combustion event. The term available air refers to the amount of air molecules that are available in the intake manifold after manifold pressure is taken into account.
The VE value used here is not a percentage of the the air available at atmospheric pressure. If this were the case, then the VE numbers would rise with rising manifold pressure. The VE values used here have already taken into account the manifold pressure, so the VE here purely represents the efficiency of the engine's ability to fill and trap the available air from the manifold into the cylinder for combustion.
These are the VE tables for the stock 4.9 and Allante. The first is the 4.9, second is the Allante. Do not worry about the change in color between the two, as the scale is slightly different between the two. Anyways, it seems at lower throttle settings and RPM the Allante intake would produce less power than the stock 4.9, but once you get to higher RPM and throttle and get into the tuned range of the runners, the power takes off. This can be seen by the sharper "hump" in the Allante table vs. the more broad "hump" in the stock 4.9 table.
That could be another reason why 4.9 Allante swaps run rich if the stock 4.9 parameters are used, in addition to the location of the air temp sensor (upper manifold in Allante, so it sees cooler temps, thus stock 4.9 adds more fuel because it thinks the air is more dense than it is). At partial throttle, the Allante VE numbers are lower than stock 4.9, but the stock 4.9 program thinks it is still making the same power as before, so it adds fuel for that power and not the lower Allante values, thus too much fuel.
------------------ 1985 GT 2.8 MT 1988 GT 4.9 AT
[This message has been edited by NJD85GT (edited 08-04-2011).]
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11:59 PM
Aug 4th, 2011
Fieroseverywhere Member
Posts: 4242 From: Gresham, Oregon USA Registered: Mar 2006
More data! I think I have too much free time... So I took those torque curves and used them to calculate accelerations, top speeds, etc. Very accurately. While the result itself may be a little off, the difference between the two should be very close.
Constants/Assumptions used: Tires 215-45R17 Trans 1 ratio: 2.92 Trans 2 ratio: 1.57 Trans 3 ratio: 1.00 Trans 4 ratio: 0.71 Trans final drive: 2.97 Frontal area of car: 19.50 ft2 Coefficient of Drag (Aero Notchback) 0.350 Air density (SL): 1.27 kg/m3 Car weight w/ driver: 3,000 lb Rolling friction coefficient: 0.015 Drivetrain loss: 15% ~2,000 RPM stall converter (I did not take into account torque multiplication, or the RPM difference once above 2,000 RPM) 1-2 shift 5,200 RPM 2-3 shift 5,000 RPM 3-4 shift 4,800 RPM
For stock 4.9: 0-60 is 5.78 sec 1/4 mile is 14.37 sec. @ 96.4 MPH Top speed is 146 MPH
For Allante 4.9: 0-60 is 5.58 sec 1/4 mile is 14.15 sec. @ 98.4 MPH Top speed is 150 MPH
Here is a graph for required crank HP vs. speed. (HP just about increases with the cube of the speed).
Here is WOT speed vs. time for the two.
Here is the force put to the pavement, both total and net (total minus drag, where net force is 0 is the top speed).
------------------ 1985 GT 2.8 MT 1988 GT 4.9 AT
[This message has been edited by NJD85GT (edited 08-04-2011).]
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02:51 AM
Raydar Member
Posts: 41116 From: Carrollton GA. Out in the... country. Registered: Oct 1999
Originally posted by NJD85GT: I used the volumetric efficiency tables to compare the two, as to tune for the Allante intake I pretty much copied over all the stuff relating to fuel into the 4.9 file. ... The base pulse constant was left alone for the 4.9 (183), since the Allante and 4.9 supposedly use the same injectors, and the ratio 4.9/4.5 is very close to 183/167 (167 for stock Allante). ...
You did pretty much the same thing that I did. (But explained it very nicely!) Just driving around and looking at the AutoXray showed the BLMs to be very close. 126-128.
I also wonder about the larger cylinder volume changing the RPM at which peak power is made. (Me being the skeptic that I am, I figure that it can't be as easy as just copying the tables across, as we have done. ) Just for grins, I'd like to be able to compare the VE tables of a 305 and a 350 TPI engine. I figure that what we're doing is quite similar.
Please do me a favor... Let me know if you have any spark knock at part throttle and medium load, at 2400-3600 RPM or so. Ever since I installed the Allante intake, I've had just a bit. You cannot hear it in the car with the windows rolled up, but you can with them rolled down. I have been able to do nothing to get rid of it.
Originally posted by Raydar: Please do me a favor... Let me know if you have any spark knock at part throttle and medium load, at 2400-3600 RPM or so. Ever since I installed the Allante intake, I've had just a bit. You cannot hear it in the car with the windows rolled up, but you can with them rolled down. I have been able to do nothing to get rid of it.
Will do! I pretty much copied your file, including your modified VE table for now. Did you try retarding the timing a degree or two in the main spark advance table for that range?
[This message has been edited by NJD85GT (edited 08-04-2011).]
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06:57 PM
Raydar Member
Posts: 41116 From: Carrollton GA. Out in the... country. Registered: Oct 1999
You would be amazed at the stuff I've tried - including that. I'm almost forced to conclude that it's something mechanical, or something really off the wall, like odd air currents through the throttle body. I don't want to hijack your thread, though.
You would be amazed at the stuff I've tried - including that. I'm almost forced to conclude that it's something mechanical, or something really off the wall, like odd air currents through the throttle body. I don't want to hijack your thread, though.
Now if you have the same issue...
Anything to do with the manual swap or didn't that change anything?
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11:06 PM
Aug 5th, 2011
Raydar Member
Posts: 41116 From: Carrollton GA. Out in the... country. Registered: Oct 1999
My 100th post after 6 years on the forum! So after doing a bit of driving around and a bunch of data logging, I seem to have a couple issues I need to solve.
I am happy to say my 0-60 has dropped from roughly around 8.0s to 6.7s, and per the current conditions I was making about 77% sea level horsepower, so SL 0-60 should be low 5's. This is due to the Allante intake, getting rid of the stock 2" exhaust, and my new diff ratio. I plan on advancing the base timing to 12-13 deg once I get everything solved.
At full throttle with an ambient pressure of 81.77 kPa, my manifold pressure steadily drops from about 80.0 kPa at 2,500 RPM to 77.5 kPa at 4,500 RPM. This shows about a 5% drop in pressure through my air filter setup at high RPM (stock can with K&N filter, restriction at bottom of can removed, 3" tubing for now). I'm not sure what the pressure would be with no intake setup, I may test it later. I plan on getting 3.5" tubing in there eventually, I just cobbled it together to get it drivable.
I am on my third alternator, and starting to get a little frustrated. The first one didn't even work, the second worked for 3 days with a low output voltage of 13V before dying, and my third one has a widely variable voltage at idle. It will vary from 12.5V to 14.2V or so, worse with load on it like brake lights, back and forth once every second or two. It is varying at the alternator, I checked with a voltmeter. Steady 14V+ above 1,200 RPM or so. I think I am going to cut up my 4.9 alt mount and remount the old 4.9 alt since I know that one worked fine.
The other issue I have is my idle is a little unstable and is very rich. My BLM's at idle are very low, 100 or so (cell #25), and vary wildly from 100-128 for all RPM ranges where learn is enabled, and manifold pressures of less than 45 kPa. I adjusted the VE table a little bit at lower RPM and MAP ranges to see how much of an effect it would have, and there was essentially no change to the BLM values. It seems to run great at higher power settings, no lack of power as noted from my much improved acceleration. I'm not really sure what the problem could be right now, so I am going to pull my spark plugs and see what I can figure out from them. I think I may have a miss at lower RPM.
From what I can tell there are 26 BLM cells, I am not quite sure what cell #25 is except that it occurs at idle and in the same range as cell #5. Here is a chart I made showing what ranges the cells are in.
------------------ 1985 GT 2.8 MT 1988 GT 4.9 AT
[This message has been edited by NJD85GT (edited 08-17-2011).]
Just a little update, I will add some pictures in the next week or two. I put the original staggered wheels back on the car and it rides much smoother now, I think I prefer these tires over the harshness of the old ones. I also solved my running rich problem, first I tried new MSD super conductor spark plug wires, then I checked compression, then I tried cleaning the old injectors, and still the same thing at idle. I finally put in some new Bosch III fuel injectors, and it made a world of difference! The engine runs much smoother now, and just sitting in the driveway, my BLM's and INT's stayed very close to 128. I still need to drive around and take some data to verify that it is good in the other operating ranges.
I have two other things I need to solve, one is there is a hesitation when taking off from a stop about 3/4 of the time, where the engine will cut out for a second before "catching" and continuing on. It has even stalled once or twice when it was really bad.
The other is I have a very very high pitched squeak under full throttle above 2,500 RPM or so about 1/3 of the time. Not sure if this is spark knock or not, as I've never hear it in person before so I can't compare it to anything. The sound is almost (not quite) one continuous note.
Nate
------------------ 1985 GT 2.8 MT 1988 GT 4.9 AT
[This message has been edited by NJD85GT (edited 09-25-2011).]
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06:46 PM
Raydar Member
Posts: 41116 From: Carrollton GA. Out in the... country. Registered: Oct 1999
I answered your PM. Spark knock is like a hammering. It's like a pile of large ball bearings inside a steel pipe, being shaken madly. A whistle is usually a vacuum leak or something similar. It might be air going around the throttle plates or some goofy thing. (Think whistling across a blade of grass.) Make sure that the holes in the TB where the shaft goes thru are not leaking.
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10:05 PM
Sep 26th, 2011
motoracer838 Member
Posts: 3751 From: Edgewater Co. USofA Registered: Jan 2006
Joe, Yeah, it's your muffler. I modified it a bit...and I learned I suck at welding with my el cheapo welder, so I'll need to get a proper exhaust made up eventually. I had to cut up your pipe that runs under the cradle too because it hit the engine mount. I do like how it sounds, it is a little smoother now than it was in that clip because I fixed the running pig rich problem. I will have to stop by, I've seen your other thread! Still haven't figured out what is wrong with the red Fiero...
Raydar, Thanks for your reply, it definitley doesn't sound like hammering or ball bearings, I'll have to try and track to sound down. There is one spot that I think I might have metal on metal contact (alt mount to chassis, tight fit) I can see some scratches so maybe that's making the noise...
So I haven't posted here in a while due to school, I'm still gathering parts. I picked up a bunch of random stuff that I need to go through. I got some new '85 GT sail panels from Fierosails to put on, as well as new emblems and new dew wipes.
Got a nearly perfect non-cracked junkyard dash for $10.
Got three unscratched door glass! A bit dirty...
Still need to find a couple sets of perfect taillights. Here's the engine as it sits today. I still need to clean it up a bit, I stuck a big cone filter on it for now.
I did some testing with two different filter set-ups: this cone filter and a stock Fiero can with the restriction removed at the bottom, and 3" tube to the throttlebody. My average manifold temps with stop and go city driving were 55 C with the Fiero setup and 70 C (hot!) with the cone filter. But, with an ambient pressure of ~ 81.75 kPa, the Fiero setup resulted in a full throttle manifold pressure of ~ 77.5 kPa, while the cone filter was at ~ 80.5 kPa. After doing some calculations, even though the cone filter give much warmer air, the lower restriction actually gives a gain of a couple HP over my stock-ish setup. So I'll keep the cone filter for now.
I hate the auto, so I may be doing a manual trans swap in the near future... I'm trying to resist the urge to stick the engine in my '85 GT since it is already stick and has some engine issues.
If you do a manual swap I might be interested in the 3.33 differential you installed.
It wasn't hard to get, it took me less than an hour to pull it out of a junkyard '92 Seville with basic tools (socket set, etc.). I went in through the wheel well, no lifting of the car was needed, it was on bricks already.
It wasn't hard to get, it took me less than an hour to pull it out of a junkyard '92 Seville with basic tools (socket set, etc.). I went in through the wheel well, no lifting of the car was needed, it was on bricks already.
Nate
Yea I know, I was just asking. But If i 'm going to change it I might as well change the chain as well and get what I want from it.
