Engine/Transmission (1994 - 1998) 300 VS 370 injectors

[Matthug]

Well got my 370's in today, have been running 300's for 6K miles now. When I installed the 300's I didn't really notice much if any increase over the stock 175 injectors... although my 175's had 250K on them so horsepower creep was likely. Today I put in 370's, I'm not too impressed. Grinding my stock plate to a 0 gives about 100 or so HP on a 175 pump, I really felt that mod big time. 370's are suppose to be like 90 HP, and I barely notice anything! I have very slightly more smoke, no idle haze (I did use the thin washers), and *maybe* 20 HP increase. I can accelerate at a normal pace with no smoke at all.

My question is this, what size holes are in 300 marine injectors? They only have 4 holes. I know 370's have 5 holes at . 012'', and my stock 175's had 5 at . 0095''. 215's have 5 at . 0105. Are 300 injectors 4 at . 012? If so that would explain why I didn't feel any power increase over the stockers. Doing the math it comes out too . 048'' total for the 300's and . 0475'' for the stockers. Now the 370's are . 060 total. So I'm not sure if 300's are . 012 since there is only 4 holes. I'm thinking maybe they are . 013 or . 014? Anybody know for sure?

 

[zstroken]

I think you should calculate the actual area, not just add up the hole sizes. That is like saying two 1. 5" exhaust will move as much as a single 3". The cross sectional area is the key. A=r^2xPi So 1. 5" exhaust 2(. 75^2 x Pi)= 1. 125Pi 3" 1. 5^2xPi = 2. 25Pi. Doesn't explain why you don't have anymore power out of the truck. Were the EGT's really high?? Maybe you need more air???

 

[Cooker]

I agree adding up the numbers means nothing.



FWIW - Last I checked 300's were . 013.

 

[bmoeller]

Something isn't right. You should smoke like a train.

 

[Bob4x4]

You can't add up numbers for every power adder you pile on... ... ... I would hook up a fuel pressure gauge first and drive it hard see what happens. . An hx35 just isn't going to work well either.



Bob

 

[Matthug]

Now that I drove the truck more tonight I'd say they are 30-40 HP over the 300's, it felt stronger tonight and the exhaust note was raspier. Also the top end gain was substantial, pulls harder up top.

I don't know about adding up the hole sizes, seemed logical to me but your analogy to the exhuast is a good one. However, exhaust gases are a whole different animal than liquids and can't really be compared like that.

I run an isspro 60 fuel pressure gauge, I only hook it up everytime I want to check the pressure because it rattles in the pillar pod and is annoying. However, I have a new PDR overflow valve, new lift pump, and last time (about a month ago) I checked I had 24-25 PSI at idle and 34 PSI at 2000 RPM no load. I have no lack of power, this truck rips!

It does smoke alot, and the poor HX35 can't keep up at all I leave a tremendous trail behind me it doesn't come close to clearing it up. Definitely way more smoke at full boost WOT over the 300's. As far as EGT's, it actually confirmed a suspicion of mine. I took a look at both the tips of the 300's and 370's. It looks as if the 370's have a much better spray angle than the 300's. Also, I used the stock thickness washers on the 300's and the thinnest ones on these 370's. My cruising EGT's are 100 degrees cooler, haven't done any prolonged WOT runs yet but they seem to run cooler than the 300's but with more power. I did about a 10 second burst of WOT on the highway, only hit about 1200 degrees running 37 PSI boost but I was almost at the governer anyway. That was on a flat grade, I have a really huge hill I can run about 20 seconds of WOT up it and it's a steep grade. I could peg the 1500 degree pyro with the 300's about 3/4 the way up everytime.

 

[bmoeller]

I didn't use the thin washers with the 370s either. That should help in the EGT department.



I have a test hill near me. Has a 45mph s-curve at the bottom, and a straight shot up the hill. When I was stock, I could barely hit 55 at the top. Now I'm doing almost 80. Oo.



Once you are able to get a better turbo, you'll be able to make better use of the fuel you have.

 

[zstroken]

I just used the exhaust example since I did that when I put my duals on. I was trying to figure out if 2. 5 would flow like a 4. Both items are fluids, granted the injector deals with a little higher pressure. The cross sectional area is what will allow the injector to flow. Plus the math was a lot easier. I didn't feel like dealing in thousandths of pi.

 

[Matthug]

Everytime I drive the truck now it seems to have more power. Although it's only 70 degrees out as opposed to 80 yesterday when I tested. Today it feels so strong it's probably 40-50 HP over the 300's, I hit defuel so fast I'm thinking 4K GSK and 60 lb springs as my next BOMB. Before it would start top dramatically loose power right at 2900 RPM but I would take it to 3200 before shifting. Now it still feels as strong at 3200 as it did at 2900 before and I shift at 3400 RPM. I really need to get 60 lb springs though, turning 3400 RPM has me worried with the stock springs with 258K on them!

Also I tested the EGT's further, 15 second burst up the hill and the pyro just barely hit 1500. With the 300's it hit 1500 faster though and I know it must have been at 1600+ degrees because it would stay pegged for a second or 2 after letting off. I am thoroughly impressed and happy with these 370's. Although I didn't test them with the thin washers I wouldn't recommend 300's to anybody.

 

[Dual EE]

I too have run both 300 and 370 marine injectors. My experience is the opposite of yours. The 300's I found were a good match with a stock turbo w/a 12 housing. Even towing 7k#, the stock turbo did an ok job keeping the egt's in check. This was a combo I liked and my truck ran strong. Dyno'd at 270 hp and 755 tq. Performance wise I agree 300's are not jaw dropping power, but in my experience they run much cooler over the 370's.



Now the day that the 370's went in, I knew that either I was going to need a bigger turbo or the 300's were going to have to go back in if I was ever going to tow again. I could easily bury my 1500* pyro on a freeway on ramp. So in went a Dodgezilla/12 and the egt's are more manageable now. Adding the 370's and the Dodgezilla I gained 77 hp. The truck runs high 14's in the quarter can get over 20 mpg if I drive conservatively. The last 370 mile road trip I netted 21. 8 mpg.

 

[Matthug]

Where did you buy your 300's from?

 

[Dual EE]

I bought them used, so I am unsure who the original vender was. I can find out if needed.

 

[Matthug]

No big deal just curious. I got mine from city diesel, they are the only ones I know of that even sell them.

 

[bmoeller]

PDR has them. I had gotten mine new from a shop in UT, via Ebay, IIRC. Same tip number as the ones PDR sells.